Chilton's Antiques

Mohs hardness scale

Was a Scale that was developed in 1812 by the German mineralogist Frederich Mohs. He selected ten very common readily available minerals and gemstones to create a scale of hardness. The scale is still use to measure the hardness of gemstones today.

Talc: The softest mineral, which can be scratched by every other mineral and also by a human fingernail. Greasy to the touch.
Gypsum: Can be scratched by a fingernail, but not easily.
Calcite: Can be scratched by a sharp coin, very easily cut with a steel knife blade.
Fluorite: Easily scratched by a knife blade.
Apatite: Can be scratched with difficulty by a steel point, and can itself scratch glass but with difficulty.
Orthoclase feldspar: A steel blade barely leaves a mark, although a file scratches it easily. Feldspar can scratch glass with ease.
Quartz: Can scratch glass, steel, copper and most other common substances very easily.
Topaz: Can scratch quartz easily and is harder than most common substances.
Corundum: (sapphires/rubies) can easily scratch quartz and topaz. Some man- made products are equally as hard, but differ chemically.
Diamond: The hardest of all natural substances. It easily scratches corundum and is very important in the industries for cutting and grinding.

Gemstones

When buying gemstones where colour is important it is wise to be aware that both the process of digital photography and the variation in computer monitors can cause a wide difference between the product and what you are seeing on your screen so always keep this in mind. Buyers also need to be educated in gemstone imitations and treatments so they understand the differences between these and natural gems.

Agate- Hardness 6.5/7

There are many varieties of agate from moss agate to layered or banded agate. In ancient Egyptian times it was used for cylinder seals, in rings, or jewellery such as cameos and for bowls and drinking vessels. It was also used as a talisman to protect the wearer from storm and lightening strikes. Agate is also one of the birthstones for June and in folklore was supposed to aid in good health.

Agate is a sub variety of Chalcedony in which it has a layered effect with bands of colours with different transparencies. A lot of agate is dyed to give it a variety of colours. One of these methods is by immersing it in a hot sugar solution followed by adding sulphuric acid and heating, this gives it a black colour.

Alabaster- Hardness 2/2.5

Is an aggregate variety of the mineral species gypsum; monoclinic crystal system. It has a chemical composition of CaSO4 2H20. Alabaster in former times was known or referred to as microcrystalline limestone this was of course incorrect. The name (Greek) came from the small cosmetic pots which were once carved by alabaster. Alabaster is sometimes dyed, and is used in ornamental pieces more so than in jewellery.

Some identifying factors of alabaster might include banded, veined or patterned like marble, with fairly dull lustre; alabaster comes in shades of pink, white or browns. Alabaster should be kept out of prolonged exposure to strong light as it dehydrates and can turn opaque and crumble. Toughness: poor. Never put alabaster in an ultrasonic or steamer, it should be washed in warm soapy water with a soft brush, as bristles may leave scratchers. Alabaster is sourced in Canada, England, Italy, Mexico and the US. Alabaster is given for the 37th anniversary.

Alexandrite- Hardness 8.5/10

Is the very rare gemstone of the chrysoberyl family (group) with the ability to change colour. The colour changes in the best gemstones from a greenish blue in daylight to an orangey purplish red in incandescent light.

This is an extremely rare collector’s gemstone found in very small quantities in the Ural Mountains in Russia. It is also located in Brazil & Sri Lanka.

The first recorded findings of this stone were in 1853 and since it displayed the Russian Imperial colours Red/Green it was named Alexandrite in honour of Tsar Alexander II.

There are huge quantities of synthetic corundum (synthetic sapphire) that were made during the 1950’s-60 to imitate this valuable stone. These rings tended to be very large and garish cocktail rings. The colour change also differs as it is a red purple- grey blue colour change not the red-green colour change seen in a natural stone.

Alexandrite is a relatively tough stone and can be cleaned in ultrasonic fairly safely.

The cat’s eye variety although even rarer again is not as resilient and should not be put in chemicals or any great heat. It is also the birthstone for February & represents sincerity.

Amethyst- Hardness 7/10

Is from the quartz group and is a silicon dioxide SiO2. Amethyst is the most highly valued stone in the quartz group. In early times it was thought to have supernatural powers to bring luck, ensure constancy, protect against magic and home-sickness.

It is found in geodes in alluvial deposits in many parts of the world, the most famous deposits come from Brazil. Bishops and cardinals used to wear amethyst as a symbol of peace and a reminder of Christ’s passion. Amethyst is featured in the bible as a holy stone. Amethyst was the stone of Ephod’s Breastplate this is recorded in GENESIS. It is also the birthstone for February representing sincerity and celebrated as the 6th & 33rd wedding anniversaries.

Aquamarine- Hardness 7.5-8/10

Aquamarine is March’s birthstone. It is from the gemstone group beryl which is the same species as emerald and its chemical composition is Be3A12Si6O18. Aquamarines are light blue, sea blue, or green in toning. Aquamarine can be transparent and if highly included can be translucent. Aquamarine can be heated to change the colour to darker blue with less green and therefore more desirable. Aquamarine was also a talisman for sailors, and the name is from Latin (water of the sea). Aquamarines can be cleaned in an ultrasonic or steamer with care, unless the stone contains feathers or liquid inclusions.

Warm soapy water would be the safest. Large quantities of Aquamarine deposits can be found in Nigeria, Brazil, Zambia, Madagascar, US, and the USSR. It is also represents courage. It is the zodiac stone for Pisces. February 19th – March 20th. The largest Aquamarine of gem quality was found in 1910 and weighed 110 kg.

Aventurine Feldspar- Hardness 6/6.5

Aventurine feldspar was discovered by chance and is quite a rare stone belonging to the aggregate family often mistaken for Aventurine Quartz or Sunstone. It is generally orange, red-brown in colour with a metallic red glitter through it, caused by the light interference on tiny platelet inclusion of other minerals. Aventurine feldspar has perfect cleavage and often a white streak can be seen through the opaque stone.

The chemical composition is Na (AISi3O8) Ca (AI2Si2O8) sodium calcium aluminium silicate. Cabochon cut with a flat surface is generally how you would find Aventurine feldspar to be cut, and should only ever be cleaned in warm soapy water not ever in an ultrasonic. It is sourced in the U.S., Canada, India, Russia and Southern Norway.

Beryl- Hardness 7.5-8/10

Beryl group of gemstones is best known for Aquamarine & Emeralds. Beryl is a group of gemstones that have the same chemical composition, beryllium aluminium silicates. This group includes a few lesser known gems. These are:
Bixbite- which is a strawberry red colour.
Golden beryl- A yellow lemon colour.
Goshenite- colourless.
Heliodore- lemon yellow to a gold colour.
Morganite- Soft pink to violet colour, this was named after the American banker & mineral collector J.P Morgan.

A majority of these gemstones are found in places such as Brazil, US & Madagascar.

Beryl is celebrated as the 38th wedding anniversary.

Bloodstone- Hardness- 6.5-7/10

Heliotrope is the gemmological name for Bloodstone. Heliotrope belongs to the quartz group of stones; this stone is comprised of opaque, dark green chalcedony with jasper flecks throughout. During the middle ages it was believed that Heliotrope possessed magical powers, as the jasper flecks within the stone were said to be drops of Christ’s blood which were supposed to protect the wearer. Heliotrope is found in considerable quantities in India, Australia, Brazil, China and North America. Heliotrope is most often found in antique seals, in men’s rings and as ornamental objects. It is one of the birthstones for the month of March and represents courage.

Blue john- Hardness 4/10

This stone is also known as Derbyshire Spar. It’s only known source is to be found in the caverns of the peak district of Derbyshire in Great Britain. It is Britain’s rarest mineral and was first discovered by the Romans around 2000 years ago. Blue John is a variety of the fluoride mineral. It differs from other flour-spar minerals as it contains banded veins of colour, in rare specimens signs of fluorescence will appear when blue john is placed under ultra-violet light. Small pieces can be made into jewellery; however blue john is most commonly used in ornamental pieces such as bowels and vases which are incredibly rare and extremely expensive.

Cairngorm- Hardness 7/10

It comes from the quartz variety of gemstones. It is smokey brown in colour, often referred to as smokey quartz and is found in different hues. It was named after one of its locations which are the Cairngorm Mountains in the Scottish highlands. These gemstones traditionally have been worn by the Scotsmen in highland dress. They wore them as kilt pins and set them in the handles of their daggers. This is also known as brown quartz and found in many other locations world wide.

Chalcedony- Hardness 6.5/10

Chalcedony has bands of colours all within the one stone. It comes in a variety of colours from white to a bluish grey. The red variety of this gem is called Sardonyx. In ancient times it was used to carve cameos. This was a very expensive and arduous task that would take many hours to carve. The finest cameos in the world were carved out of this material. Normal shell cameos are very soft with a hardness of only 3/10 making them by far an easier material to work with. Chalcedony is also known as hardstone for this very reason. It was also used as a talisman against going mad and depression. Sardonyx is one of the birthstone for August and represents a happy marriage in early European cultures.

Chrysoberyl- Hardness 8.5/10

Chrysoberyl is named from the Greek meaning “golden beryl”. This came about at the end of the 18th century. Before this it was mistakenly called peridot or other yellow gems. This gemstone is predominately a yellowish green colour, which is a colour similar to and was popular in Victorian jewellery. There is also a range of greenish brown colours.

There are two varieties of chrysoberyl that are probably better known, Alexandrite and the cat’s eye variety. The cat’s eye or chatoyant effect is due to fine parallel inclusions producing a silver white vertical ray that moves across the stone in the light. The name was derived from this effect as it looks exactly like a cat’s eye. This is found in Sri Lanka, China & Brazil.

The most expensive varieties of Chrysoberyl are the Alexandrite & the cats eye, some of these stones maybe stones be worth hundreds even thousands of dollars per carat, making them one of the world’s rarest & most desired gems. Cats eye chrysoberyl is given as the 18th wedding anniversary.

See Alexandrite for more information on this.

Chrysoprase- Hardness 6.5/7

This is considered one of the most prized chalcedonies. It comes in a variety of green colours from apple green to a greenish yellow. This is usually cut into cabochon cut gemstones & beads. It was used extensively in the Victorian era for rings and brooches. It is often confused with jade, and green glass can often be passed for this.

It is found in Queensland Australia and Brazil. The best material today is mined in Queensland.

Citrine- Hardness 7/10

Citrine is the birthstone of November and is the zodiac sign for Gemini May 21st –June 20th. It is also used to celebrate the 13th wedding anniversary. Citrine belongs to the quartz group. Citrine varies in colour from light yellow to golden brown. Pale yellow is the most common colour of natural citrines. Deposits are located in Brazil, North America, Spain, Russia, France and Scotland. Citrine stones of a good colour and size are often fashioned into rings, pendants, earrings and necklaces. Citrines were also used in seals. Citrine can often be confused with other yellow gemstones such as tourmaline, beryl and especially topaz. Citrines were very popular in World War II as it was difficult to obtain gems from the Far East. Cartier produced an interesting range of multi-coloured citrine jewellery. Large set Citrine rings were also very popular. Citrines are available in a number of hues ranging from yellow and orange to golden brown. Queen Victoria set the trend of the day by having a love of Scottish pebble jewellery which was set Agate, Jasper, Freshwater Pearls and Citrine.

Cinnabar- Hardness 2-2.5/10

This is a colourful mineral that is used in jewellery. It comes in a variety of colours from scarlet red to cinnamon. Cinnabar was mined by the Roman Empire for its mercury content. It was also favoured by the Chinese. Jewellery referred to today as cinnabar usually tends to be a heavily moulded resin based polymer as any jewellery actually containing mercury would be too dangerous. This bright colour is sometimes referred to as ‘dragon’s blood’ by the Chinese. The Chinese for centuries have used this stone for carvings & for doing inlay work for jewellery & other artefacts. It is found in China, USA, Spain & Serbia just to name a few world sources.

Carnelian- Hardness 6.5/10

Carnelian’s name is derived from a type of cherry- the kornel cherry, because their colours are so similar. Carnelian colour ranges from a flesh red to a reddish brown colour. Main sources are from India & Brazil. In antiquity it was thought to soften anger & still the blood. It is often used with bloodstone in spinners & engraved for family seals & crest rings.

Crystal-

A widely used term to cover everything from the quartz variety of colourless rock crystal, to the glasses we drink from, to grandma’s beads that she once wore. This term can be all three. The word crystal originates from the Greek word ‘krystallos’ meaning ice. Quartz or rock crystal is a naturally occurring mineral that was once believed to be ice or rock that was eternally frozen. This has a hardness of 7/10 on the Mohs hardness scale.

The other widely used term- crystal is a man made substance, made buy heating silica, soda ash (sodium carbonate) & limestone (calcium carbonate). These are all melted together in a furnace at very high temperatures. Lead crystal is also just termed ‘crystal’. Lead crystal is really just glass that has had lead oxides added to give glass a higher dispersion and improve optical performance. The presence of lead also makes the glass easier to cut. This process was discovered by George Ravenscroft an Englishman in 1676. Glass has been around since early civilisation- Romans & Egyptians had basic forms of this technology. Crystal may be given for the 3rd & 15th wedding anniversaries.

Cubic Zirconia-Hardness 8/10

The name of these stones is often abbreviated to CZ. It is claimed that experts cannot tell the difference between cubic zirconia stones and diamonds however this is a very misleading statement. To the untrained eye this may be the case, however trained gemmologists can definitely differentiate the two stones. Cubic Zirconias are synthetic diamond simulants. Cubic Zirconias are hard, durable stones that have few inclusions, usually colourless but can come in many different colours and are inexpensive to create.

Cubic Zirconia’s can be purchased for as little as a few cents to a couple of dollars per stone. The main differences between these stones and diamonds are their chemical composition and their hardness. Cubic Zirconias are softer than diamonds and they are sensitive to high temperatures. They are not intended to be a quality stone or something that will be kept long enough to become a family heirloom, but just a low cost inexpensive stone that is worn for costume jewellery. There is an abundance of C.Z's being sold at present. A machine called a diamond probe/tester has been invented to help in the aid of the detection of the CZ. It works on the fact diamonds have the ability to conduct heat. This tester is a small battery operated device that enables heat to travel through the stone & measure it. This is used by people in the jewellery industry who are not skilled gemmologists or diamond graders.

Diamond- Hardness 10/10

In early times diamonds were reputed to endow the wearer with purity, love and joy. THE DIAMOND- ‘admass’ of the Greeks is the traditional symbol of fearlessness, the unconquerable. It is the hardest of all natural substances. Its chemistry is carbon. Diamonds are the birthstone for April. Diamonds represent purity and innocence. Diamonds are also used to celebrate the 10th, 30th, 60th, 75th, 80th & 85th wedding anniversaries. Diamonds have a hardness of 10 which means they are the hardest of all gemstones. Diamonds occur in a wide range of colours. From: colourless, brown, yellow, green, pink, black, red & blue. The rarer the colour the more value a stone has. The most common colours are yellow and brown in the varying degrees of intensity. If a diamond has a strong intense colour it is termed a “fancy” and may increase its value.

Diamonds are valued on their quality like other Gemstones.

There are the 4 C’s Cut, colour, clarity & carat weight (size) see our facts section for more information.

DIAMOND FACTS:

CARAT- Is a term given to the Weight of the gem- the size of the stone.

COLOUR – Is the body colour of a stone. The colours start from D and go to Z in the white series. The whiter the stone the more valuable it is, as the grades get lower on the scale the price drops accordingly.

There is also a brown series of diamond, that scale again is less valuable then the whiter stones.

CLARITY- Is the natural internal and external characteristics of a diamond, whether these are other minerals growing (dark black markings) or white feather like markings.

THE SCALE OF CLARITY:

FL- Flawless, free from internal & external flaws

IF- Internally flawless, no inclusions

VVS- Very, very slight inclusions

VS- Very slight inclusions

SI- Slight inclusions

PK- “Pique” or spotted diamond. Large inclusions visible with the naked eye

Cut- Is a measure of the diamond cutters ability to cut a diamond’s specific proportion to a set formula that has taken many years to perfect. If a cutter cuts a stone too deep or too shallow a diamond may have a lower degree of brightness or scintillation

Sub division of the clarity grades VVS, VS, SI & PK split into two sub groups each. These are also used for stones over 0.47ct in size. See diamonds for more facts & a chart.

Doublets-

These are stones that are composite and are made of two pieces. They are stones that are put together forming an unnaturally occurring gem. This could be for example a Garnet and glass doublet which is a thin slice of garnet which is fused by glue to a glass (paste) base. GTD’s are often seen in many antique jewellery pieces and were used in the making of jewellery for the working class in Europe, due to its inexpensive nature. This can be seen with the aid of hand lens to look for join lines and also air bubbles trapped within the glue. With other gem stones there can be doublets. One example is ruby & sapphire synthetic doublets. Like garnet topped doublets they have a natural ruby or sapphire top then they have a synthetic ruby or sapphire bottom. These are cemented together in such a way it can be difficult to pick up to the untrained eye, especially if set in jewellery.

Another common doublet is an opal doublet. Opal doublets of the 1920’s are still very sought after today as their colour & their internal play of colour can be very remarkable. This was often done as there were some very good quality seams & veins of opal found but they were too thin to be cut as a solid stone so the opal needed to have backing material added for extra strength & durability. This was usually potch or black glass to create the effect of a black opal. [ref. opal section]

Triplets are the same type of process as doublets but there are three layers not two. Again with opals there is a thin colourless top, a centre thin slice (veneer) of opal and black potch all glued together.

Emerald- Hardness 7.5-8/10

Emeralds belong to the Beryl group of gemstones. The name Emerald is derived from the Greek “Smaragdos” meaning green stone. The name emerald has been used from the 16th Century. Emeralds range in colour from a deep velvety green to grass green. The most valuable emeralds are a deep green colour. Emeralds have been around since early biblical times & it was said that at the last supper Jesus Christ supposedly drank from a cup made of emerald. Other famous historical connections include Cleopatra, Pliny & the Queen of Sheba who all adored Emeralds.

Often emeralds contain inclusions or ‘jardin’ which are the result of liquid or gas bubbles, foreign crystals or healing cracks. These jardin are evidence of the genuineness of the stone. Emeralds are found in deposits in Brazil, Columbia, America, Austria, Russia, Australia, Zimbabwe, Tanzania, South Africa, Ghana, Zambia, West Pakistan and India. Emeralds are the birthstone for May and are believed to bring beauty to their wearer. Warm soapy water is recommended as ultrasonic cleaning can be very dangerous. Some stones can also be enhanced through either oiling, to hide their natural inclusions or dyeing, to enhance their colour. As the birthstone for May they represent success. Emerald is the gemstone for the cancer star sign, June 22nd – July 22nd. It’s also used to celebrate the 20th, 35th & 55th wedding anniversaries.

Foiled back gemstones-

Foiled gemstones were commonly used in early Georgian jewellery as a backing behind flat and dull gemstones or cut glass to give them more dispersion to liven up their appearance. This was due to less proficient cutting technology. Foil behind gemstones is often patchy, ruined by water logging. This is seen in Georgian and Victorian period jewellery especially in seals and paste jewels. In the 1940’s-1950 this technique was revamped for the diamantes in the rhinestone cocktail jewellery. Foiling was not only done to genuine semi precious and precious gemstones like amethysts, diamonds and citrines but also to glass and paste.

Fluorite- Hardness 4/4.5

Fluorite is generally too soft, but can be used in jewellery with care. Its hardness is too low to resist much wear & tear. It comes in a wide colour range from colourless, yellow, brown, green, blue, violet & pink. Fluorites massive variety is known as Blue John. It is found in Western Germany & South Africa. Cleaning in warm soapy water is the only recommended way to clean this gem, ultrasonic cleaning is not recommended.

Garnet- Hardness 7-7.5/10

There a wide variety of garnets depending on their chemical composition. Garnets come in many different varieties such as Almandine, Pyrope, Spessartite, Grossular, Uvarovite, Hessonite, Demantoid (anradite) & Tsavorite. The word Garnet is derived from the Latin word for grain, because of how the crystals are found- in rounded forms. In the Victorian period people favoured garnets and they were faceted into rose cuts and used in Bohemian jewellery. It is usually safe to clean garnets in an ultrasonic but with some varieties more care must be taken.

In folklore garnets represented friendship, consistency and faithfulness. It is also the birthstone for January. It is also the zodiac stone for Aquarius – January 20th – February 18th. It is used to celebrate the 2nd & 40th wedding anniversaries. In ancient times it was said that these were magical gems and could give good health to the wearer. It was to protect against injury and poisoning, to stop bleeding, inflammation, anger and agitation, bring honour to a person and guard against mishaps while travelling. The varieties of garnets are listed below. Most people do not realise that garnets come in a range of colours from red, orange, purple red, yellow, light yellow green & green.

Almandine garnet- is a dark red variety of garnet which is similar in colour to some rubies. Some stones can be a reddish orange while others are a red purple.

Andradite - is a calcium-iron garnet and is of variable composition and may be red, yellow, brown, green or black. The recognized sub varieties are topazolite (yellow or green), demantoid (green) and melantite (black). Andradite is found both in deep-seated igneous rocks like syenite as well as serpentines, schists, and crystalline limestone. Demantoid has been called the "Emerald of the Urals" from its occurrence there, and is one of the most prized of garnet varieties. Topazolite is a golden yellow variety and melanite is a black variety.

Demantoid garnet- demantoids are a very rare and expensive green variety of the garnets. This is found in very small quantities in Russia (old source) & Africa (new source). This garnet was often used in antique jewellery and is easily identified buy its identifying characteristic inclusions known as the “horse tail”. These are yellowish needles that radiate out from of the centre and are very distinctive.

Tasavorite garnet variety of the Grossular garnet-

A gorgeous transparent green that arguably rivals the best emerald for saturated colour and brilliance. Only discovered in Tanzania in 1968 and then later discovered in Kenya it was named by Tiffany & Co. after the Tsavo National Park.

Uvarovite garent is a calcium chromium garnet found in small crystals too small to be cut into stones. This is a rather rare bright green garnet, usually found as small crystals associated with chromite in peridotite, serpentinite, and kimberlites. It is found in crystalline marbles and schists in the Ural Mountains of Russia and Outokumpu, Finland.

Hessonite (Grossular) garnet- Is a yellowish orange reddish orange colour.

Malaia colour change garnet- Pinkish orange – reddish orange to a yellow orange. Some show a distinctive colour change in different lights. Their major source is East Africa.

Rhodolite garnet- Are a purple red colour and are very attractive, one of the most popular garnets. Their value in recent years has risen due to their popularity. They are found in Sri Lanka, Zimbabwe & Tanzania.

Spessartite garnet- is a yellowish orange coloured garnet that is found in Australia, Burma & India.

Mali Garnet or Grandite Garnet

Mali garnet is fairly new to the market. They have only been marketed since 1995, Mali garnets are found in western Africa in the Republic of Mali. They are seen in various shades of green, yellow or brown. These “new” garnets often resemble faceted chrysoberyl, and their prices are some what similar.

Garnets were also used in creating composite stones. These were known as GTD- Garnet topped doublets. This was comprised of a very thin top layer of garnet being cemented to a glass (paste) bottom. The Garnet and the glass were placed in a mould and heated in a furnace. After cooling down it is then faceted. The paste bottom determines the colour of the stone not the garnet top. Doublets can be seen in any colour red, blue, green & yellow are most common. Garnet was chosen for these doublets as it was the easiest stone to fuse to glass.

Glass- Hardness 5-6/10

Glass is a man made material. Also see Crystal. Glass is often known as Paste. This cheaper material was often pressed into shape in the moulds to save to cost of faceting. More expensive varieties were faceted. It can come in a variety of colours and appearances. It is a composition of silica, mass produced for low cost jewellery. It can also be called rhinestone jewellery- some of these were even foiled from behind like a mirror to give them an added diamond like appearance. Goldstone is a glass with orange copper metallic glitter spread throughout, often seen in Victorian jewellery especially in Nanny Brooches.

There are some natural varieties of glass such as obsidian, moldavite & tektite.

Tektites are produced naturally when a meteor impact has occurred. This is found in places such as the Libyan Desert or outback Australia. It is usually safe in ultrasonic cleaner, but remember glass has a low melting point.

Garnets were also used in creating composite stones. These were known as GTD- Garnet topped doublets. This was comprised of a very thin top layer of garnet being cemented to a glass (paste) bottom. The Garnet and the glass were placed in a mould and heated in a furnace, after cooling down it is then faceted. The paste bottom determines the colour of the stone not the garnet top. Doublets can be seen in any colour red, blue, green and yellow are most common. Garnet was chosen for these doublets as it was the easiest stone to fuse to glass.

Hematite- Hardness 5.5-6.5/10

Is a metallic looking gemstone that is black to dark grey in colour. It has a metallic lustre and is often used to carve intaglios, seals & round beads. In ancient times it was used as a mirror. It was also used as an amulet against bleeding. Its name is derived from the Greek word for – blood. It has a red streak so when it is being cut fine particles are red. It is mined in Norway, Sweden & England. It can react to heat and may become magnetic so much care must be taken when working with this gem. It is safe in an ultrasonic cleaner.

Iolite- Hardness 7-7.5/10

Is a blue gemstone available in many different hues. It is also incorrectly called the water sapphire. This name can be very misleading as it is not at all related to Sapphires and is a different mineral. The name iolite comes from the Greek word for Violet. Main deposits are in Burma, Sri Lanka and India. Extra care must be taken when cleaning this stone and it is recommended to be cleaned in warm soapy water not in ultrasonic fluid. Jewellers also must take care when working with this stone. This gem cannot be put in direct contact with heat. Iolite is given for the 21st wedding anniversary.

Jade- Hardness Jadeite 6.5-7/10 Nephrite 6-6.5/10 -

There are two different varieties of Jade: Jadeite and Nephrite. Jade is one of the birthstones for August and in early cultures it also represented a happy marriage. Jade is celebrated as the 35th wedding anniversary.

Jadeite

Jade is semi translucent to opaque. It comes in a variety of colours- apple green, dark green, black, purple (lavender) & white. Jade is often dyed to enhance its colour. It is usually heated to open the pores to allow the dye to seep in. Also it can be treated with paraffin wax to hide fractures and improve the polish (finish of the gem). Special care is needed; it is recommended that you avoid strong solvents, acids and high heat. In China it is used for good luck and is a means of expressing rank and authority. There are many glass imitations of this very precious gem and gemstones can even be seen as doublets. The major source is China and Burma.

Nephrite

Nephrite has very similar characteristics to jadeite. It is more common than jadeite; it is the less expensive of the two jades. It is also commonly known as green stone and New Zealand jade. It comes in a variety of colours; green both dark & light, whitish yellow (mutton fat), brownish yellow (tomb jade), white grey, black and often mottled (spotted effect). Like Jadeite it can be dyed and colour enhanced in similar ways. It is exceptionally tough and outranks jadeite. This toughness was often used to make weapons, tools and ritual ornaments. Untreated material can be cleaned in an ultrasonic. It is found in New Zealand, South Australia, Burma, Australia, Brazil & Poland.

Jasper-Hardness 6.5-7/10

Jasper is considered a chalcedony, a part of the quartz family. Its name is derived from the Greek word for spotted stone. It comes in a wide variety of colours brownish reds, yellows-blacks. Deposits are located all over the world in India, Germany, U.S. & Russia just to name a few. It is popular in the making of mosaics. In antique jewellery it was used for this as well as seals and worn as an amulet against drought. It is one of the birthstones for the month of March and represents courage

Kunzite- Hardness 6-7/10 Member of Spodumone group.

Kunzite is a pinkish violet colour. It was named after G.F Kunz who first described the gem in the Edwardian period-1902. This is a difficult material to work with for gem cutters and jewellers, as it has a perfect cleavage and in directions it is very sensitive to pressure. If it is dropped it the stone can split. It is also very sensitive to heat including strong sunlight. It is found in large crystals in the US, Brazil, & Burma.

The green variety is called Hiddenite and they are both from the spodumene group of gems.

The name spodumene is derived from the Greek word meaning “burnt to ashes” a reference to the non gem variety of moderately large crystals. The only recommended way to clean this gem is with warm soapy water.

Labradorite- Hardness 6-6.5/10 Member of the Feldspar group.

Labradorite was named after the Canadian peninsular of Labrador where in 1770 this stone was found. It has play of colour called Labradorescence or schiller - an interference effect similar to oil on water rolls over this grey metallic like stone. It is sensitive to pressure. It is used for beads, carvings and ornamental objects. It is located in Russia, Canada, US, & Finland just to name few. Cleaning with warm soapy water is recommended, never harsh chemicals or ultrasonic cleaners.

Lapis Lazuli- Hardness 5-6/10

Is a combination of lazurite, calcite & pyrite. Its name is derived from the Persian word-“lazhward” meaning blue stone. It is rock, comprised of several minerals. A majority of Lapis is dyed to improve the colour and disguise calcite (white) inclusions. It is very sensitive to pressure & high temperatures. It has a vitreous to greasy lustre.

The most important deposits are located in Afghanistan, these mines have been worked for over 6000 years. In the year 1271 these mines were visited by Marco Polo. The stone has been used in jewellery for centuries. There are also many imitations of lapis on the market but a keen gemmologist can always pick this up. Lapis imitations are often dyed a dark blue colour and have a greyish tinge. Other better imitations are also available on the market with more convincing gold flecks.

Sodalite is often mistaken and used as imitation for Lapis Lazuli; however it is not as valuable. Soadalite never reaches the beautiful deep ultramarine blue seen in lapis. Sodalite also has alot of white calcite inclusions and usually contains little to no flecks of pyrites.

Lapis is usually cut into cabochons, carved or made into beads. The best way to clean lapis is with warm soapy water. No harsh chemical cleaners or ultrasonic cleaning. Lapis Lazuli is given for the 9th wedding anniversary.

Malachite- Hardness 3.5-4/10

Is a layered green ornamental opaque stone that comes in a wide rage of greens. The Cause of colour is due to its chemistry which contains copper. It has a formation, which has a botryoidally concentric circle like pattern formation with circular banding. It has a silky lustre. It was a favourite gem of the Russian Tsars, who used it to decorate their palaces. In ancient times the Egyptians, Greeks & Romans used it in jewellery of amulets and ground it into powder for eye shadow. In the middle ages it was thought to cure vomiting and protect against witches. It is usually carved into beads, statues and ornaments. It is recommended cleaning in warm soapy water only and can be very easily scratched.

It is located in many countries such as Zaire, Australia, England, France, Namibia, South Africa, Romania, US and USSR.

Moonstone- Hardness 6-6.5/10. Part of Feldspar group

Was named after its blue white sheen that is caused by its lamellar structure. Because of this it is usually cut into cabochons to give the best effect. It comes in variety of colours white, whitish blue, yellow & brown. It is sensitive to pressure & heat. There are many deposits found- Sri Lanka, Burma, Australia, Brazil & India just to name a few. There are many imitations out there in the market place, the easiest way to identify imitations is to look for moonstones diagnostic inclusions- small stress cracks known as centipedes or Chinese writing. The most valuable colour is the billowy blue colour seen in older antique pieces. It is a feldspar mineral. Best way to keep it clean is warm soapy water, ultrasonics are not advised. Moonstone is also the birthstone for June and in folklore was suppose to aid in good health.

Moldavite- Hardness 5.5/10

See glass- natural. It is apart of the Tektite group. It is formed when rock has melted after being hit by a meteorite. These are found in Australia, the US & Czechoslovakia to name a few countries of origin.

Onyx- Hardness 6.5-7/10

Is a Chalcedony, it is opaque and can have parallel layers of different colours. The Art Deco period saw the reinvention of Onyx accessorising it with diamonds and using the contrasting colours for a stunning effect. Other periods such as the Victorian Mourning period saw onyx used in a strict code of etiquette. These strict codes applied to the widow’s dress codes. Today onyx is used in jewellery to recreate these styles and can be cut into many different shapes. Scratched pieces can be bought to life again by having them repolished. It is also the birthstone for Leos and for the 7th wedding anniversary. It is located in many places all over the world and is fairly tough; care must be taken when wearing it not to scratch the shiny black surface. Dyed Chalcedony is often used as imitation onyx.

Opal- Hardness 5.5-6.5/10

Opal’s distinctive play of colour makes it one of the most highly valued and attractive of all gemstones. An opal’s body and colour determines its value. The brightness, range of colours, pattern, body colour, consistency and directionality of the colour within the stone determine an opal’s value. It is transparent to opaque in appearance with a rainbow like play of colour that changes with the angles it is viewed at. It has an amorphous crystallographic structure with water content 3-20%. Thus opals should be kept with water to prevent drying out and cracking (this is only for solids not triplets or doublets). There are few types of opals- Black, White, dark, crystal (jelly) and fire opal. These are put into three basic categories: Precious opal- opal that exhibits play of colour, Potch opal- Opal that does not show play of colour, Common opal- Opal That does not show play of colour but has some degree of micro crystalline structure. There are other terms used in the description of opal patterns such as- Pin fire- the small close set patches of opal, Harlequin opal- angular regular patterns of opal, Flame opal- reddish bands, Flash opal with sudden flashes that quickly disappear or change as the stone is moved, peacock opal- play of colour is predominantly blue & green and Lechose opal- Green only play of colour. A good quality opal is a very highly prized gem and can be worth thousands of dollars

Boulder opal is seen when a thin layer of opal with play of colour is cut on the rock in which it forms.

Opalized wood- Occurs when the wood is replaced by opal. Known as “Xylopal” the same thing also happens to shell. Opals should never be cleaned in ultrasonic and heat should be avoided as they are susceptible to cracking. The best way to clean them is in soapy water. Opals are also sensitive to pressure and are relatively soft. They can be damaged very easily. Scratching however is not a problem- a good gem cutter can always re-polish them. It is the Birthstone for October and is used to celebrate the 14th & 34th wedding anniversaries. The diamond industry in the eighteenth & nineteenth century orchestrated the spread of rumours that opals were unlucky and would bring misfortune to the wearer. This is said to have come about due to their popularity in jewellery. Diamond merchants were worried it would affect business. About this time the influential novelist Sir Walter Scott wrote of Anne of Geierstein who owned an opal and played an evil part.

Major sources of opal in Australia are: NSW- Lightning Ridge & White Cliffs. QLD- Winton, Quilpie, Kynuna, Opalton & Cunnamulla. SA- Coober Pedy, Mintabie & Adamooka. Also found in Brazil & Mexico- Fire opals. Some of the requirements that opals need to form are water, stable terrain, faults or cracks in the earth to allow water to settle and a sedimentary environment with a source of silica. Opals are commonly seen as doublets and triplets. The doublet opals of the 1920’s are still very sought after today as their colour and their internal play of colour can be very remarkable. This was often the case because there were very good quality seams and veins of opal found but the stones were too thin to be cut as a solid stone so they needed to have backing material added for extra strength & durability. This usually tended to be onyx to create the effect of a black opal.

Triplets are the same type of process as doublets but there are three layers not two. Again with opals there is a thin colourless top, a centre thin slice (veneer) of opal & quartz backing all glued together. This is the more economical version of the opal. This also creates the effect of a black opal.

Imitation opals can also be found in doublets & triplets. Presently there is a surplus of treated and imitation material on the market so beware!!!

Peridot- Hardness 6.5-7/10

Peridot is also known as the gem of the sun. Peridot is the birth stone for August and the zodiac sign of Leo July 23rd-August 22nd. Peridot is also used to celebrate the 16th wedding anniversary and like many gemstones there are many superstitions attached to it. Examples are the ability to dispel night terrors and to ward off evil sprits. Historically peridot has been used, in a powdered form to alleviate the symptoms of asthma and was placed under a patient’s tongue to ease thirst during a fever. Peridot ranges in colour from green, greenish yellow, yellowish green, greenish brown to brown. Peridot has distinctive inclusions that look like Lilly pads. Period in antiquity was known as Olivine, due to its colour.

Peridot is found in deposits in Egypt, North America, Hawaii, Norway, China, Tanzania and Australia. Peridot may be confused with tourmaline, chrysoberyl, synthetic spinel, zircon and glass.

Cleaning is best done in warm soapy water, ultrasonic cleaning is considered risky. It can react to heat and stones may fracture & completely break. Peridot is one of the birthstones for August & in early cultures represents a happy marriage. It was known as the gem of the sun.

Pyrite & Marcasite

Pyrite is Greek for fire- when knocked it produces sparks. It is a brassy yellow metallic colour & it is often known as fools’ gold. It has a metallic lustre and is found all over the world. The Incas used it as mirrors.

This mineral is the disulphide of iron and is closely related to Marcasite, which has the same composition.

Marcasite- This is pronounced as “marcazeet”. It is a mineral that is faceted into small flat backed rose cut stone and is usually set into silver dress jewellery. The Victorian marcasite jewellery was usually pyrites. Marcasite is a separate stone. They both have different crystal systems & there are other minor differences. Marcasite is not as chemically stable as pyrites & this makes it useless for jewellery purposes. The 1920’2-1940’s saw the height of this fashion with the early original vintage pieces now becoming highly desirable.

The original true marcasites were a bronze metallic coloured stone. This was very popular in Europe from the 1900’s. Marcasites are usually set in silver rarely in gold, and are rose cut. Marcasites are made from iron pyrites and were an inexpensive imitation of diamonds. These were called “cocktail” jewels or “black diamonds”.

The best quality vintage marcasites jewellery was made in Germany. Today a lot of copies and reproduction marcasite jewellery is made in Asia and it is quite easily spotted from the original pieces. The stones are glued not claw or bead set and they are mostly cast and hollowed out. Popular items were marcasites earrings which were generally screw on style, necklaces, bracelets and brooches.

Quartz- Hardness 7/10

The quartz gems comprise of several different varieties & groups. These include a wide variety of gems- Rock crystal (colourless), Smokey quartz (brown), Amethyst (violet), Citrine (yellowy-brown), prasiolite (weak green), Rose quartz (pink), Aventurine (green iridescent), Tiger eye (yellow-golden brown), chalcedony (white-bluish-grey), carnelian (reddy brown), chrysophrase (apple green), Heliotrope (dark green with red flecks), moss agate (colourless with green inclusions), Dendritic agate (colourless with reddish brown & black with tree like fern images), Agate (various colours banded & layered together), jasper (white, yellow, brown-red), Opal (white, gray, blue, green).They have the chemical composition of silicon dioxide.

Rhodochrosite- Hardness 4/10

Is a lovely rose red to white striped, ornamental opaque gemstone. The name refers to the colour- it’s Greek for rose red. The major locations it is found in is Argentina, Australia, Germany Romania & Spain. It is recommended that it be cleaned in warm soapy water and never cleaned in an ultrasonic.

Rhodonite- Hardness 6/10

Is very similar to Rhodochrosite, the major difference is the black dendritc inclusions that are mottled throughout the stone. This stone can be found in the Ural Mountains, Sweden, US, India, South Africa & Mexico. It is usually cut into beads and cabochons.

Rose Quartz- Hardness 7/10

Rose quartz was named after its colour & comes in a variety of transparencies from semi transparent to translucent. The shades of pink often do vary in tone and it always tends to be cloudy. It is becoming increasingly popular today in jewellery in beads. The best sources of rose quartz are found in Brazil, Madagascar & India.

Ruby- Hardness 9/10

It is often difficult for the public to believe that sapphires and rubies are the same mineral. Ruby comes from the Latin term Rubeus meaning red, rubies are coloured by chromium. Rubies belong to the corundum group. Rubies are the second hardest minerals after diamonds and vary in colour from a fine blood red, pinkish, purplish and brownish reds. Rubies are particularly popular in Asian countries as they were used to decorate noblemen in India and China. They were also buried beneath the foundations of buildings with the view of securing good fortune.

Ruby is the birthstone for July and in early society represented passion and contentment. It’s the zodiac sign of Capricorn, 22nd December to 19th January. It is also the 15th & 40th wedding anniversary stone. Legend states that the owner of a fine ruby was said to be assured of a peaceful life & neither his land nor his rank would be taken from him. Rubies are also said to preserve the health of the wearer, for a ruby removes all evil. An unusual and naturally occurring phenomenon known as Star stones are seen in rubies. These highly prized and sought after gemstones have needle like rutile inclusions that are arranged in three sets of parallel needles that intersect one another at 60® angles. It creates a star like phenomenon that will roll with the angles of light. The quality of the stone is judged on the sharpness of the star. There are a huge number of synthetic stones now available on the market.

Sapphires- Hardness 9/10

Sapphires have a long and varied history. Sapphires are known to be the birthstone for September and the zodiac stone of Taurus, May 20th- April 20th. Sapphires are also used to celebrate the 5th, 45th & 85th wedding anniversaries. They represent wisdom and are said to be the gem of the soul. It was worn in early times to preserve the wearer from envy. In early cultures sapphires were thought to be able to empower people with the ability to influence spirits. In the twelfth century the Bishop of Rennes began the use of sapphires in ecclesiastical rings. It is often difficult for the public to believe that Sapphires and Rubies are the same mineral. Sapphires, like rubies, belong to the Corundum group. Blue sapphires are coloured by Iron and Titanium.

Star stones are available in sapphires. This occurs when a stone has needle like rutile inclusions that are arranged in three sets of parallel needles that intersect one another at 60® angles. It creates a star like phenomenon that will roll with the angles of light. The quality of the stone is judged on the sharpness of the star. There are many synthetic sapphire stones available on the market.

Sapphires come in a wide range of colours- Blue, dark –light, Orange, pink, yellow, & green. Parti coloured sapphires have two or more colours seen within the one stone. This is usually green, blue & yellow.

Kashmir Sapphires have the reputation as the most valuable sapphires. They are a fine bright blue. Sapphires are found in Australia, Thailand, China, Africa, Sri Lanka, and India.

Smokey quartz- Hardness 7/10

Smokey Quartz belongs to the quartz group. It ranges in colour from brown to black and a smokey grey colour. Smokey quartz is found world wide. These stones may be confused with anadalusite, tourmaline and idocrase.

Spinel- Hardness 8/10

Many of the famous historical rubies including the Black Prince’s ruby in the British Royal Crown jewels have now been indentified as spinels by gemmologists. Spinel has a different chemical composition to that of ruby although their colours can be somewhat similar. The ‘Timor’ ruby which is also in the possession of the British Royal family is actually a spinel. The name spinel first seems to have appeared in the 17th Century and its meaning is derived from the Latin word “spinella” referring to its crystal shape. It comes in a wide range of colours from colourless to red, yellow, green-blue, violet, black, purple, orange, brown, grey & even pink. This stone is often unrecognised and discounted by the general public which is a shame as it has so many wonderful properties. Spinels are one of the most synthesized gemstones. At the turn of the century and today many synthetic stones are found in antique jewellery. It is located in many countries such as Sri Lanka, Tanzania, Afghanistan & Myanmar. The prices of spinels today are quite high as they are gaining in popularity. Spinel is given for the 22nd wedding anniversary.

Tanzanite- Hardness 6.5-7/10

Tanzanite is also known as a member of the gem group Zoisite. Tanzanite was named after the East African state of Tanzania where it is found. It was first introduced by the New York Jewellers Tiffany & Co 1967. The colours this precious gem is found in are- bluish purple violet mixture & Khaki. Extra care needs to be taken when cleaning these stones and ultrasonic cleaning is not recommended due to hardness. It is also the gemstone for the 24th wedding anniversary.

Tiger Eye- Hardness 7/10

Has a fibrous gold and silky structure with brown iron producing the golden yellow colour. This fibrous structure is known as ‘chatoyancy’ it is very sensitive to chemicals. It is from the quartz family of gemstones. The major sources are located in South Africa, Australia (WA), Burma & India.

Topaz- Hardness 8/10

Stones come in a range of colours, mostly pastels. The most common colour is yellow; the most valuable is pink. It is the birthstone for November and represents happiness, it is also given as a gift for the 4th wedding anniversary. Citrine is often sold as topaz. Often the blue colour is heat treated and topaz can be irradiated. When cleaning use warm soapy water, avoid harsh chemical cleaners and ultrasonic devices as topaz can be very easily cleaved. Dropping it on hard surfaces can split the stone in half. Avoid rough handling. The most important sources are Sri Lanka, Burma, Russia but it is found in many other countries such as Mexico & Australia.

Tourmaline- Hardness 7-7.5/10

Tourmaline has been used in antiquity for many years in jewellery. The Dutch were some of the first people to import the stone from Sri Lanka into Europe in the 18th century.

The stone has piezo-electricity properties, so when rubbing a crystal piece it becomes electrically charged one end (negative) and positive on the other. Charged tourmaline was used to attract small pieces of paper or dust.

Virtually all known colours will be displayed by tourmaline. It has a variety of colours: pink, red, green, orange, blue, black, violet & brown. World sources include Brazil, Afghanistan, Angola, Australia, Burma, India, Africa, soma parts of the US & Thailand just to name a few. Cleaning is best in warm soapy water and it is best to avoid ultrasonic and harsh chemical cleaners. Tourmaline is celebrated as the 8th & 38th wedding anniversaries.

Turquoise- Hardness 5-6/10

Turquoise ranges in colour from sky blue to green. Persian (Iranian) turquoise is still the most desired being a lovely bright blue colour. The other type of turquoise that is widely known is the Mexican Native American turquoise with clay matrix inclusions.

The name turquoise means “Turkish stone” as that was the trade route taken to bring the stones to Europe via Turkey in the 19th century. The colour can change with exposure to excessive light and chemicals such as perfume, hairspray, oils, perspiration or creams. The main sources are Iran, Afghanistan, Eastern Australia, Tibet, Tanzania & the US.

Imitation turquoise is also available on the market. Natural Turquoise is very expensive and very hard to find these days. Its appearance will show if it is fake as many items that are labeled turquoise are not all they seem. Cheap artificially man made stones have been expertly dyed to imitate natural turquoise, even the black veins are reproduced in the imitation turquoise. Imitations are made from epoxy resins and are generally lighter in weight and don't have the same cold to touch feel that a real stone has. Imitation turquoise beads In ancient times Turquoise was used in tribal jewellery, amulets & also in cosmetics The Persians wore turquoise to protect against unnatural death. Examples of turquoise were found in Egyptian tombs dated over 7000 years ago. It has actually been known since 3000BC and possibly even prior to that. Furthermore it was thought to connect the sky and the sea in ancient superstition and today is often used as a good luck talisman by people flying, especially pilots. It is one of the birthstones for December and represents an unselfish nature. Turquoise is the zodiac sign for Aquarius, January 21st- February 18th. It is also used to celebrate the 11th wedding anniversary.

Zircon- Hardness 6.5-7.5/10

Zircon was known and used in antiquity. Zircons were mentioned in the Bible and carved stones have even been recovered from very ancient archaeological sites. Zircons were believed to aid sleep and to bring prosperity and promote honour, wisdom to the owner.

Zircons come in a wide variety of colours :blue, violet, red, green, orange, colourless, yellow & brown. Stones are often heat treated which is a stable form of altering a gem’s colour by placing it though excessive heat. An example of this process is blues and colourless stones

Avoid rough wear since stones tend to abrade. The stones have strong dispersion and doubling of the back facets, thus giving off an intense brilliance and fire.

The best way to clean them is in warm soapy water; it’s very risky to clean them in an ultrasonic.

These gems are found in Sri Lanka, Burma, Thailand & Australia (Central Australia & in the sapphire fields).

Some colours can be unstable with light.There are 3 types of Zircons- High type: red brown orange colourless,;intermediate type & low (metamict) type :green, brown orange & yellow.

Organic Stones

Amber- Hardness 2-3/10

Amber is a fossilized resin from pine trees. Amber was formed approx 30-50 million years ago before the great Ice Age. There are many different types of amber, from sea amber found in the Baltic Sea to Silesian amber. The best and most efficient way to test amber is with a hot point probe. The smell emission is a pine tree odour. This is usually a destructive test and not always recommended.

Other ways to test amber is that it will float in salt water and also visually with a hand lens looking for inclusions such as Lilly pads or sun spangles.

There are many plastics that are used to imitate amber. One of these imitations is the early Bakerlite faceted beads of the 1930’s. Amber and plastic can be melted and mixed together to form an amberoid composite material.

Amber is found in many places, such as the Baltic Sea amber. After a big storm it can float to the surface of the water as the ancient tree forests are now many meters under the sea. With all the turbulence from the storms, the amber floats up to be either washed up on the beach or to be fished out by people skimming it off the surface.

Pit amber is mined by open pit mining, digging down into the ancient fossilized forests.

Amber is available in a wide range of colours orange, yellow, red, green & blue.

Often amber is heat treated and oiled to clarify it. This produces what is known as sun spangles which are disc like lily pad inclusions that can be seen under magnification.

Major sources are Dominican Republic, Baltic coast of East Germany, Poland and Russia.

Cleaning is best done in warm soapy water with an old tooth brush with soft bristles. Never use any chemicals, hot water or an ultrasonic cleaner.

Bog oak- Hardness 4/10

This is a dark brown to ebony coloured wood that was used mostly in mourning jewellery. It has a matt finish. It is found in the peat bogs of Ireland. In the peat bogs usually a variety of trees is found, the Pine tree, Oak and the Yew tree. The type of tree the piece is can usually be determined by the colour of the material used. Oak bog material is an ebony colour while the Yew or the Pine tree is a light fawn or brown colour. The Oak is the tree that is used in the making of jewellery. The black colour that is seen in Bog oak is from a chemical reaction from the Gallic acid of the wood with the iron held in the water of the bog.

Bog woods are retrieved from the bog lands where they have been buried for over 5000 years and have come to the surface. It was used in jewellery for the making of brooches, mostly seen as a hand holding a bouquet of flowers. There are also many pieces with Irish related symbols i.e. harps, castles and shamrocks or Celtic crosses relating to its Irish origins. This is usually the telltale sign that it is bog oak. Nine out of ten times an Irish symbol will be a guarantee that it is bog oak. Look for moulded edges and rounded edges with raised stippling and the intricacy of design that cannot be achieved by a hand tool as in jet. This was used to imitate jet and became popular in the 19th century. It is a similar substance to jet coming from fossilised wood, mainly oak trees. It is only found in the peat marshes of Ireland. Bog oak is always carved not moulded; this shows its wood like grain. The fittings on these pieces were usually metal painted black but gold could be used sometimes as well. Burnt bog oak smells like burning wood with a hot point probe This is usually a destructive test & not always recommended.

Brooches are often seen with scenes of the Muckross Abbey House and the Abbey which were both close to Killarney which had a flourishing tourist trade because of this local carving industry.

When the timbers are first bought to the surface from the airless depths of the bog they are medium to dark brown colour but on the contact with oxygen semi petrification soon sets in causing the wood to darken. Therefore if a piece is to be carved it needs to be started straight away to enable the piece to be worked easily.

Bone

Bone is often confused with Ivory as it is a similar substance when first looked at. Bone like Ivory is opaque and is found as a whitish material and then is often dyed.

On closer examination you can see the differences. Bone will have a Haversian canal which is left over from where the blood was flowing through the bone. The bone will often have these reddish brown lines throughout it, which is dried blood. These lines can be viewed best under magnification. In some cases this will not be visible, as the bone will often be bleached to remove this effect.

Coral- Hardness 3.5-4/10

Coral is an organic material. It is the remains of a colony of tiny marine animals that make a skeleton like structure. It is found in a variety of colours dark red, pink, light pale pink (angel skin) orange, white-creams and black. Some of the colours can be dyed by the method of impregnation with epoxy (glue like material).

In folklore coral represented consistency and faithfulness. It is also one of the birthstones for January and celebrated as the 35th wedding anniversary. When tested with a hot point probe a smell of burning hair is emitted. This is usually a destructive test and not always recommended.

It should be cleaned with warm soapy water, never heated & rough wear is to be avoided. The major sources are Australia, Japan, Philippines, Mediterranean sea along the coast of Italy, Algeria, France just to name a few.

GUTTA PERCHA

This is a natural polymer similar to a natural rubber however the properties are quite different from rubber. Gutta Percha is the name of a tree (Isonandra Gutta) native to the Pacific regions. The sap from the tree is evaporated and the resulting product is latex. This was first introduced to the West by William Montgomerie in 1843. He demonstrated the material’s ability to be heated and moulded. Gutta Percha was also used to insulate electrical cables as well as a cheaper substitute for Jet in mourning jewellery in the mid 1800’s. The Gutta Percha company was founded by Dr. Montgomerie in 1845 and was in business until 1930.

Horn- Hardness 3/10

Horn is a darkish brown colour that is literally horns from an animal. Animals such as: stags (deer), rhinoceros & bulls or wildebeests. Horn depending on its finish can have a lacquered appearance and like bone can have blood vessel like Haversian canals. It is usually used in carvings and for inlays. It can dry out in time and pieces should avoid sunlight as it can bleach them.

Ivory- Hardness 2.5/10

Ivory is from a variety of sources it is a broad term not only including elephant tusks but the teeth of hippopotamus, narwhale, sperm whale, walrus, sea lion, wild boar and fossilized woolly mammoth tusks. Ivory is a prohibited import into most countries and there have been sanctions put in place to prevent the needless slaughter of animals for no other gain then the trade in their tusks. Ivory has very identifying marks from where the hair particles have formed over one another creating a weaving or cross hatching effect; this is known as engine turning. These lines are very visible in certain sections and make indentifying ivory very easier.

The best way to clean it is warm soapy water. In very early Victorian jewellery we see such things as, early Chinese ivory carved beads, netski (carved oriental miniature figures)and scrimshaw (whales/walrus tooth that has been carved into by sailors when at sea). Most of this is imitated on today’s market. The imitators go to a lot of trouble to stain pieces and to imitate the aging process even producing marks that would indicate wear and tear. Many early plastics such as ivorine were used to imitate ivory. The hot point test will confirm that it is ivory or an examination for Haversian channels in bone and cross banding indicate true ivory. It is also fairly soft from 2-3 in hardness and chemical composition is calcium phosphate. With bone you can spot Haversian channels where the blood flow was moving though the bone and you can still in some cases see the brown staining on pieces if the bone has not undergone bleaching.

Jet- Hardness 2.5-4/10

Jet is an ancient organic stone that was formed millions of years ago from compressed wood of the ‘Araucaria’ tree or other wise known as the monkey puzzle tree, a pre historic tree that grew in dense forests. This tree existed in the Jurassic period 180 million years ago. These trees were subjected to a chemical reaction when they died and became drift wood- flattened by great pressure for millions of years. The colour varies from black to dark brown. It was used mostly in the Victorian era for mourning jewellery. One of the largest deposits is found in England in a place called Whitby where it was mined at the turn of the century.

The town of Whitby has been cutting and trading in jet for centuries. Today there is still a very active trade in jet at Whitby. There are over 15 jewellers retailing the organic stone for the tourist trade but only two or three cutters. At the peak of the jet industry there were 1700 towns folk employed in the jet work shops. Today jet is still cut, shaped and polished by hand using traditional skills handed down through the generations. Jet mining is prohibited as the cliffs are now protected. However due to natural erosion from the cliffs, jet is often washed up within a seven mile radius of the cliff face or picked up from the base of the cliffs on the shore.

Jet is not to be confused with French jet. French jet is actually an imitation made from black glass. Compared to organic jet, French jet is very shiny, heavy in density and is darkish purple in the light. An easy way to separate Jet from its imitations is it has a lighter density than French Jet and Onyx. Jet is also warm to touch not cold like onyx or glass. Jet is also easily scratched with a hot needle and it gives the smell of burning coal. Mostly all jet is hand carved so you can look for signs of those carving lines. Jet is often carved with a Yorkshire rose to symbolizing the Whitby heritage.

Jet fractures fairly easily, so great care needs to be taken when carving a piece. Jet is also a carrier of static electricity and when rubbed against wool or hair will lift tissue. Jet’s streak is light brown to dark brown when scratched and the best jet has a darker streak and a velvety waxy lustre. Jet was used for mourning jewellery in Victorian times from 1860’s onwards after the death of Queen Victoria’s husband Albert. Her grief plunged the country into a period of mourning so it quickly became the fashion. Today jet is still worn as stylish everyday Jewellery by men and women. Jet also does come from other locations in Europe but it not as sought after as the Whitby variety as the colour of the material does not have a darker streak. Jet when tested by a hot point probe will emit the smell of burning coal. This is usually a destructive test & not always recommended.

Kauri gum

Kauri gum is more recent fossil resin, and isn’t as old as amber. It is also known as copal. It, like amber, will float in salt water and has a slightly tackier feeling than amber and when rubbed emits the same strong pine smell as amber. Kauri gum is found in large deposits in the north of New Zealand. The surface is often crazed. The best way to keep it clean is warm soapy water.

Pearls- Hardness 2.5-4/10

Pearls are one the true wonders of Nature. Once they were a natural phenomenon but today they are big business. It has been said that pearl’s traditionally were formed by a grain of sand or a shell fragment being trapped inside an oyster. Through time this caused the oyster to secrete a silky substance called ‘nacre’. Nacre was produced by the oyster to coat the irritant (grain of sand). Today they are produced by collaboration between Nature and man. The cultured pearl came about in 1900’s when a Japanese man Kokichi Mikimoto was the first to invent the techniques needed for the cultivation process.

The most accurate way to distinguish between a cultured pearl and a natural pearl is by taking an X-ray. When an X-ray is taken the natural pearl will show concentric circles like a tree ring, while a cultured pearl will have rings and also a bead (shell) nucleus.

Pearls are also the birthstone for June and in folklore were supposed to bring good health. They are also traditionally given as a gift for the 3rd, 12th, 30th & the 80th anniversaries.

On the market today we see a wide variety of qualities of pearls such as:

Seed pearls are small half domed pearls that range in size from 1mm up to 4mm. These where often used to accent gemstones from Edwardian times to Georgian times. These small half pearls grew on the sides of the oysters and are usually natural. Abraham Lincoln was said to have paid $2,600 for a string of seed pearls and a pair of matching earrings from Tiffany's for his wife, Mary. Seed pearls have always been very pricey. This is due to the fact that for every 100 they harvest from an oyster only a few survive the process of being cut out intact.

Akoya pearls are from the much smaller Pinctada Fucata oyster and are predominantly farmed in Japan. These were the first type of pearls that were able to be cultured. They reach 6mm-9mm in size. The most famous of all these pearls are the ‘Mikimoto’ branded strands. These can be set apart from other cultured pearls by their outstanding quality and their famous “M” trade mark located on the clasp. In recent years, due to over farming of the land, these pearls have developed a greenish tinge that has had to be bleached off. This is due to fertiliser run off from the land.

Mabe pearl is the cultured half pearl that forms on the inside lip of the oyster. This does not happen by chance but rather by inserting a domed shaped nucleus. The smaller variety of this is the seed pearl.

Keshi pearl is formed by chance in an oyster. This can either happen in the wild or on a pearl farm. It may happen by chance without human intervention. Keshi pearls usually have an irregular shape and range between 2-10mm in size; bigger pearls than this have been known to be found. These are usually sold by gram weight. They are still rare and sought after however do not quite fetch the high prices that south sea pearls can obtain. Keshi pearls are the closest thing to a natural pearl. These are formed by chance in salt water.

South sea cultured pearls are the largest of the cultured pearls. They are also considered the best quality. They range from 10mm to 15mm in size and are known to grow even larger (20mm) however these are extremely rare. They are grown in the pinctada maxima oyster, a very large oyster mostly found and cultured off the coast of Broome in Western Australia. The cultivation of pearls is an extremely expensive process .Vast amount of time, money & resources are put into their growth. The pearls are hung in baskets in the sea, where they grow in farm designated areas. These baskets are constantly checked and turned by divers to promote even growth. It takes approximately 2 years to grow a single pearl.

The Tahitian varieties are produced by the black lipped variety of the Pinctada margaritfera oyster. These are located in the South Pacific and come in a wide variety of black tones. They grow in size from 8mm to 16mm.

Fresh water cultured pearls are a rapid farm pearl produced in huge quantities from oysters farmed mostly in China in freshwater rivers. This industry has seen rapid growth in recent years. This has taken place due to the costly nature of saltwater pearls so a cheaper alternative had to be found. Fresh water pearls come in a wide variety of sizes and are produced in fresh water. Their sizes usually range from 2mm-10mm. The culturing process that is used can produce pearls quite rapidly and are usually cultured in the oysters for a shorter period of time, compared with the saltwater pearls. This is done to reduce cost.

Often these cultured pearls are lower quality as they have not had long enough to grow. This can often affect the coating that is over them, which is known as the nacre. It can be very thin and often the mother of pearl bead that they have used to start the cultivation off with is visible. Small strands of these pearls can be picked up for less then $10, larger strands of better quality are more expensive.

Freshwater cultured pearls come in a variety of colours from white to off white, yellow, pinks and blacks. A majority of the fancy coloured pearls seen today are either bleached or dyed. Some of the colours they are dyed include browns, blacks, greys, blues, green, purples and pinks & any other colour.

Pearls have sheen or lustre to them known as the orient of pearl.

All pearls can be assessed on the following characteristics -

Size: Measured by their diameter in millimetres.

Colour: Silver, silver pink, white, cream, rose, pink, gold, white gold, grey, green& black tones.

Lustre: Is the amount of light reflected from a pearl’s surface. This is directly related to the nacre. Many even layers of nacre are required to achieve this visual effect.

Shape: Many shapes are available from round, off round to teardrop and baroque. The rarest and most valuable is the seemingly flawless round shape.

Blemishes:

Are the tiny marks seen on the pearl’s surface. Blemishes occur in a different ways. Some examples of how blemishes occur are by sea mites burrowing into the oyster’s shell and attaching to the pearl’s surface, sea particles scratching the pearl’s surface. The fewer the amount of blemishes, the more valuable the pearl will be. They are best seen by taking the strand and placing it flat across a table and rolling it with your hands. It then shows you the entire circumference of the pearl, picking up all the surface flaws.

Natural Pearls at one time were considered the most valuable commodity in the world even more valued then diamonds.

Quandong nuts

This small round hard seed was often dried and used in jewellery. This is grown on the Quandong fruit tree. The Quandong is an indigenous native Australian tree. The nuts were collected by Aborigines and strung together. This also became a popular past time among the early colonial Australians. These nuts where often carved with messages and tokens of love. Seeds were made into bracelets, pendants, lockets, earrings and necklaces.

Shell- Hardness3.5/10

Shell is an organically formed material that comes from a living animal. There are a wide variety of shells used in the jewellery industry. When talking about shells, usually the first thing that comes to mind is Cameos. The two types of shell used to carve cameos are the Helmet shell- which is a two toned layered shell that is white and brown or white and orange and the Conch shell which is pink to orange in colour. Most cameos are carved out of these two varieties of shell, the Helmet or the Conch. Cameos can also be carved from other materials such as the Quartz variety agate and are known as hard stone cameos.

Cameos can also be made from glass or even lava. Cameos are usually a lady’s face in profile which has been carved against a darker lower background. This was traditionally a Roman art associated with intaglios. These artisans were trained in the centres of Rome and Florence and set up workshops in Prague, Paris and London. The carver’s influences were inspired using episodes from the Bible, images of Christ, the Virgin Mary and Saints, Roman & Greek mythology. Other popular subject matter was Diana the Roman goddess of Hunting, The Three Graces & Medusa. Other varieties of shell are-

Operculum – The Operculum is a white, green and brown shell with a cat’s eye like appearance. The name operculum is derived from the Latin meaning lid or cover. This was used by type of shell fish as a cover for when they retire back into their shell. During World War II these were extensively collected by the troops in Papua New Guinea, Darwin, Vietnam, Fijian Islands, Tahiti and Samoa. Often jewellery brooches, bracelets and earrings are seen set with this shell.

Mother of pearl- Is found inside many various shells. This is the part that has the pearly lustre. This is often carved, used for buttons, knife handles and inlays in other ornaments such as furniture and card cases. There are many varieties of shell used for this. They come in a wide range of colours from whitish grey though to the greyish, greenish bluey tones of the Paua & Abalone shell.

Mareener shell- Is a shell that was used in the traditional Aboriginal craft of shell necklace making. The impact that the early colonial settlers had on Aborigines was devastating. The Europeans brought with them disease and violence. The Aboriginals fled to Cape Barren and Flinders Islands to the North East Coast of Tasmania where these shells were found. The Mareener shells are now in short supply and are considered very precious. Some very good examples of long muff chain lengths are in Museum collections around Australia. It can take months or even years to collect enough to produce a long necklace. They can only be collected at certain times of the year. This pain staking process involves- collecting them, cleaning them and stringing them. These necklaces are considered to be national significance to indigenous Australian art. This was a traditional aboriginal women’s craft. They also often traded these necklaces with the early European settlers. The small sized shells are a greenish, purple bluish colour and have an iridescent lustre.

The shells mentioned above all come from a majority of the world’s tropic & sub tropic locations. Shells are best cleaned with warm soapy water. Care must be taken with them when cleaning as they are very soft and old shells can be brittle.

Tortoiseshell or Pique- Hardness 2.5/10

Tortoiseshell comes from the species the Hawks-bill turtle. These inhabit the tropical & sub tropical areas such as the West Indies, Brazil, Island of Celebes & the Malay Archipelago. It has a mottled brown speckled coloured shell which is where the term pique comes from. Tortoiseshell is semi translucent. The colour is made up of round spots of colour, the closer the spots are together the deeper the colour is. Tortoiseshell is warm to touch. When tested with a hot point probe, it smells like burning hair. This test is not recommended as it is very destructive.

This was used in the 1800’s as a popular form of jewellery. Items made from tortoise shell included hair combs, fans, pendants, crosses, bangles, bracelets and brooches. The shell was boiled in hot water to release the plates, as they were thermoplastic. Thirteen plates were released from one shell. These were then moulded into jewellery with gold and silver inlays. Stars, moons and swirls were pressed into some designs making these pieces highly desirable.

When testing this gemstone it is better left to a specialist as the hot point probe method of testing can be very dangerous and is not recommended.

How do gemmologists tell the difference with so many gemstones around? We test them by various means:

The common Hand lens-

10x magnification- Looking at the stone’s surface, focusing on the interior of the stone, looking at the back facets of the stone.

Polariscope- This tests whether a stone is singly or doubly refractive.

Refractometer (RI) - Measures the way light travels though a gemstone and gives a numerical reading.

UV lamp- Long and short wave tests the fluorescence and phosphorescence of gemstones and how they react to light. For example glass or paste will glow a bluey green fluoro colour under long wave while a dark blue Australian Sapphire is Inert (stays dark- has no reaction).

Microscope- Enables you to look deep inside the stone to see things that the hand lens couldn’t detect. It also shows gemmologists stones in different lights, such as “dark field” Illumination, achieved by an indirect light source. Inclusions- internal marks with in a gemstone are extremely important for gemmologists to correctly indentify a natural gemstone from a created one. For example fingerprints and feather like inclusions are seen in sapphires and rubies. While in synthetic sapphires and rubies such things as fine dust patterns are often seen when undissolved powder is used in its manufacture.

Specific Gravity- S.G machine aids gemmologists to measure the density of gemstones in water.

Spectroscope- An optical instrument used to measure a gemstones spectrum. This also tells gemmologists by the dark lines seen how a gem has achieved its colour and its composition.

Thermal Conductivity probe (diamond tester) - - This is used to measure the thermal conductivity of a gemstone to determine whether it is a diamond or an imitation gem. There are also moissonite tester that looks some what similar to this instrument,that tests between diamonds and moissonite (substance that looks very similar to a diamond and will test as a diamond by using a normal diamond probe).

Chelsea Filter- A small hand held device that filters out certain wave lengths of light so substances can only appear red, green or brown. This helps in detecting what a gemstone maybe and also if it has been dyed. It only works on red, green and blue coloured gemstones.

This also will tell us if a gem stone has been treated. Many gemstones have had one form or another of treatment some are acceptable, some are not! Treatments should always be disclosed, you need to know what you are getting for your money.

Gemstone groups

Corundum Group

Rubies and sapphires they both have the same chemical composition but have different colouring agents. Chromium is in ruby for the red and Iron and titanium is found in sapphire to give it the blue colour.

Beryl Group

Emeralds (green), Aquamarine (Blue), morganite (soft pink-violet), Heliodor (yellow) & goshenite (colourless) & Bixbite (Strawberry-red).

Chrysoberly

Alexandrite & Chrysoberly cat’s eye.

Garnets

Pyrope (dark red), Almandine (reddish brown), Spessartite (orange, reddish brown), Rhodolite (red violet), Grossular (yellow green-copper brown), Demantiod (bright green) Tsavorite (dark green) & Uvarovite (emerald green).

Tourmaline

Ruberlite (pink-red), Dravite (yellow-brown), Verdelite (green), Indicolite (blue), Siberite (violet blue), Schrol (black).

Spodumene

Hiddenite (yellow-green), Kunzite (pink-violet)

Quartz

Rock crystal (colourless), Smokey quartz (brown), Amethyst (violet), Citrine (yellowy-brown), prasiolite (week green), Rose quartz (pink), Aventurine (green iridescent), Tigers eye (yellow-golden brown), chalcedony (white-bluish-grey), carnelian (reddy brown), chrysophrase (apple green), Heliotrope (dark green with red flecks), moss agate (colourless with green inclusions), Dendritic agate (colourless with reddish brown with tree like fern images), Agate (various colours banded & layered together), jasper (white, yellow, brown-red), Opal (white, gray, blue, green).

Jade

Jadeite (brown, blackish, violet, green, white, reddish and yellow), Nephrite (white grey-dark green, reddish-brown).