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Gem by Gem

Gem by Gem

Choosing a Gem

A gemstone is the naturally occurring crystalline form of a mineral, which is desirable for its beauty, valuable in its rarity and durable enough to be enjoyed for generations.

There are more than 40 popular gem varieties and many more rare collector gemstones. Although some gemstone varieties have been treasured since before history began and others were only discovered recently, they are all nature's gifts to us.

Please enjoy surfing through our Gem by Gem list of the world's most fascinating gemstone varieties. 

 

Diamond

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Not necessarily colourless

It really is not our job here at the International Colored Gemstone Association to tell you all about diamonds. However, diamond is the modern birthstone for April, so we would like to take this opportunity to say a few words about fancy coloured diamonds, which are more to our taste than the colourless type: they're rarer, more valuable, and a great deal more colourful (although the colours do tend to be a little on the pale side).

Fancy coloured diamonds are not a mass-market product such as those which are advertised everywhere and sold by numbers. They have more personality than that. Fancy coloured diamonds are almost as much fun as coloured gemstones! Like coloured gemstones, each one is different. They come in fabulously expensive pale pinks and blues, pale to bright yellows, oranges, greens, and all those brown colours that are now given names like cognac and champagne. So, buy a diamond instead of a coloured gemstone if you must, but at least consider a fancy coloured one which will give your jewellery more character, more individuality and more colour!

 

Pearls

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Very cultured

Pearls are organic gems, created when an oyster covers a foreign object with beautiful layers of nacre. Long ago, pearls were important financial assets, comparable in price to real estate, as thousands of oysters had to be searched for just one pearl. They were rare because they were created only by chance.

Today pearls are cultured by Man. Shell beads are placed inside an oyster and the oyster is returned to the water. When the pearls are later harvested, the oyster has covered the bead with layers of nacre. Most cultured pearls are produced in Japan. In the warmer waters of the South Pacific, larger oysters produce South Sea cultured pearls and Tahitian black cultured pearls, which are larger in size. Freshwater pearls are cultured in mussels, mostly in China.

The quality of pearls is judged by the orient, which is the soft iridescence caused by the refraction of light by the layers of nacre, and lustre, the reflectivity and shine of the surface. Fine pearls do not have any flaws or spots in the nacre: it has an even, smooth texture. Other factors which affect value are the regularity of the shape, size, and colour: rose tints are the most favoured.

Cultured and natural pearls can be distinguished from imitation ones by a very simple test. Take the pearl and rub it (gently!) against the edge of a tooth. Cultured and natural pearls will feel slightly rough, like fine sandpaper, because of the texture of natural nacre. Imitations will feel as smooth as glass because the surface is moulded or painted on a smooth bead.

 

Jasper

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Landscape in stone

Jasper is an ornamental rock composed mostly of chalcedony, microcrystalline quartz, in association with other minerals, which give it colourful bands and patterns. Jasper was a favourite gem in the ancient world; its name can be traced back in Hebrew, Assyrian, Persian, Greek and Latin.

Jasper is often named according to its pattern: landscape jasper, the most popular, offers a small panorama in stone. Ribbon jasper, picture jasper, and orbicular jasper are the names of other varieties. Jasper is found in many countries. It is sometimes used to create bowls and other objects and to adorn buildings, such as the Saint Wenceslas Chapel in Prague.

 

Bloodstone

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The martyr's gem

Bloodstone, green jasper dotted with bright red spots of iron oxide, was treasured in ancient times and served for a long time as the birthstone for March. This attractive chalcedony quartz is also known as heliotrope because in ancient times polished stones were described as reflecting the sun: perhaps the appearance of the gem reminded the ancients of the red setting sun, mirrored in the ocean.

Medieval Christians often used bloodstone to carve scenes of the crucifixion and martyrs, for which reason it was also dubbed the martyr's stone. According to the legend about the origin of bloodstone, it was first formed when drops of Christ's blood fell and stained some jasper at the foot of the cross. A beautiful example of carved bloodstone with the seal of the German Emperor Rudolf II can be seen at the Louvre in Paris.

Even today, finely pulverised bloodstone is used as a medicine and aphrodisiac in India. Perhaps that explains why it is now rather difficult to find fine specimens of bloodstone on the market. Bloodstone is mined in India, Australia, and the United States.

 
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