Jewellery Catalogue co.uk

GEM STONES Descriptions

CORAL from the Greek word Korallion , is an organic substance made from the skeletons of a small invertebrate ,the coral polyp. It varies in colour from white to pale pink ,known as angel skin to orange and deep red known as ox blood ,there is also black coral.Red and pink are the most valued colours.
It is formed in sub tropical waters and thrives in a narrow temperature range of 13 to 16 degrees centigrade.It was popular with the Victorians and the best orange red colour comes from the Mediteranian around Algeria and Tunisia.It is also found in the sea near Naples and off the coast of the Italian islands and Japan.
Coral is usually made into beads or cut as cabochons and was very fashionable in the 19th century for the reproduction of classical cameos.Pieces like small twigs are often sold as brooches or carved into figures flowers and animals
Coral reefs are now protected due to the effects of pollution.



JET
is very light and is a form of wood fossil.It was popular in Victorian times,particularly after the death of Prince Albert.Jet is found in Whitby,Yorkshire,although some was imported from Spain.In Whitby,jet carving became a cottage industry.
French jet is a term used for moulded glass,imitating jet.



TORTOISHELL has nothing to do with tortoises,it is from the sea going turtle found in the pacific ocean and west indies and was used in 19th century jewellery,often inlaid with gold or silver pique work.Moulded tortoishell was used in Victorian lockets,earrings,chains boxes,combs and snuff boxes.



AMETHYST the word comes from the Greek word Amethistus meaning sober



They were found in Germany,India,Sri Lanka Russia,Ireland and Burma but since the 19th century they have come from Brazil and Siberia

They used to be classed as rare and were used for Royal jewellery in the 18th and 19th century but in 1850 with the discovery of large amounts of Amethyst in Brazil, prices dropped.

A rich deep purple stone is a sign of quality.



CITRINE the word comes from the French word citron, meaning lemon
It is a member of the quartz family, related to the amethyst.
It is usually yellow but can be reddish brown or reddish orange.
Natural citrines are found in Brazil and are rare.
In the 19th century they were used in place of expensive Topaz.

Cartier incorporated citrine into a range of jewellery.

Most stones sold as citrine are really smoky quartz or heat treated amethyst.



GARNET the word comes from the Latin Granatum meaning pomegranate
It is made from silicate and was found originally in Russia, Sri Lanka,India and the Czech Republic
Today the mines are found in Brazil ,Mozambique,The Czech Republic and Madagascar

There are many colours of garnet through red, purple ,yellowish brown and green



SPINEL comes in a wide range of colours through red, blue, violet, and pink they are found in Burma and Sri Lanka and are formed from magnesium aluminium oxide

The large central stone in the Imperial State crown, made in 1838 and called The Black Prince ruby is in fact a spinel



TURQUOISE Constantinople was the trading place for turquoise which comes from Iran, The Sinai Peninsula and more recently Mexico

It is a hydrous phosphate of copper and aluminium
It was very popular in the 18th and 19th century because of its bright blue colour and its affordability.
The best turquoise is uniform and flawless but acid from the wearers skin can discolour it.



AMBER is organic, made from carbon and succinic acid,it is a fossilised pine resin, sometimes containing natural insects.The name is derived from the Arabic word Anbar meaning to burn

Colour varies from pale yellow to brown to dark red and should be quite clear.Most amber has been submerged for about 30,000,000 years and dates from the ice age.The Victorians used amber in jewellery and in the Art Nouveau and Art Deco period long amber beads were worn.It is found in the Baltic, Burma,Italy,Alaska ,Canada, America and the lebanon and the red sea.

GREEN AMBER does not occur naturally. The term green amber is generally misused and is in fact copal which comes from Colombia or East Africa and has been heat treated in an autoclave to make it green. This resin has not matured long enough to be correctly termed amber and should be called copal.
 

RUBY The word comes from the Greek Ruber meaning red
Rubies after diamonds are the most valuable gem in the world
They are red coloured corundums formed from aluminium oxide

Up to the 16th century all red stones were called carbuncles
A Bohemian ruby was actually a garnet
A Brazilian ruby was actually a Topaz and a Balas ruby was a spinel
The traditional source of ruby was Burma, Thailand ,India and Sri Lanka
They have also been found in Vietnam, Tanzania and Afghanistan



EMERALDS The word comes from the Greek word Smaragdos
Until the late 19th century all green stones were called Emeralds
They are from the Beryl family and in ancient times were only found in Egypt, but in 1492 they began to arrive from the New World
Today they are mined in Brazil, Pakistan, Zimbabwe, Zambia, and Russia
The best stones come from Columbia but the most important emeralds came from India in the 16th century

Good emeralds are a deep rich grassy green and lesser emeralds are paler and less brilliant



SAPPHIRES The word comes from the Greek word sappheirus meaning blue

Fancy sapphires can be pink, red, purple, yellow ,green or brown

In the 16th century sapphires were not valued as highly as other precious stones

Up to the 19th century they came from Sri Lanka and Burma
In 1870 they were found in Australia and Thailand and in 1881 deposits were found in Kashmir, where the best sapphires now come from.



DIAMONDS Coloured diamonds are known as fancy diamonds ,they are the most prized
DIAMONDS come in many different colours, they are a form of crystallised carbon, the hardest substance known Only one in every 100,000 stones has a deep enough colour to qualify as a fancy coloured stone.
Green is caused by radiation and the colour is rarely evenly distributed through the stone.
Yellow is caused by nitrogen and found in South Africa
Dark green and blue are caused by boron and found in India
Pink is found in tiny quantities in Tanzania, Brazil and India and in larger quantities in Australia, red is the rarest colour
Black is caused by enormous granite inclusions and is normally used industrially although black diamonds have recently become fashionable. Diamonds were known in Europe from the time of the Romans
They were named from the Greek word Adamas which means invincible
They were valued for their magical qualities and hardness and in the Middle ages used in powdered form as a poison
Very small amounts came to Europe until the Rennaissance and by the 16th century table - cuts and diamond points showed the brilliance of the stone, even though settings were enclosed and gave a darker brilliance
In Europe in 1620 the rose cut was used ,this was a dome of faceted triangles on a flat base
Inthe 17th century greater brilliance was noticed through the 58 faceted brilliant cut
This is still the most widely used cut today

In the earlier years, India was the source of diamond mines until 1725 when they were discovered in Brazil and in 1866 they were found in South Africa
During the 20th century Russia, Canada, and Australia have discovered diamonds





TOURMALINE Tourmalines from Brazil are a bright electric greeny blue colour and are called Paraiba tourmalines. This terminology has evolved to to mean a particular shade of copper bearing elbaite tourmaline. There are a lot of copies of this stone including apatite, synthetic beryl, cubic zirconia and glass.



PEARLS At the start of the 20th century there were 3 pearl dealers for every diamond dealer but now there are 1000 diamond dealers for every pearl dealer. The Japanese introduced cultured pearls in the early 20th century. In the Persian Gulf, oil was discovered and this provided employment for former pearl divers. The pollution caused by the oil reduced the yield of the oyster beds. There is only one small active fishery in the world for natural pearls and that is in Kuwait. As there is only a small natural pearl production today, most people will look to the alternative of more affordable cultured pearls.
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