Jewelry Lovers

This large and miscellaneous collection of gems are all crystalline or micro-crystalline silicas of one kind or another. Silica is one of the commonest substances in the earth’s crust and it has been calculated that quartz represents 12 per cent of all rocks on the earth. By no means all this quartz is usable for gems, but nature has produced many strange and beautiful things from this material. The commonest type of crystalline quartz, the colourless, pointed rock crystal, is only rarely cut as a gemstone. When faceted, rock crystal is rather glassy looking and lacks fire and lustre. It has, however, a very important role in everyday life: if an electric current ispassed through it, it pulses regularly and is therefore used to _control timekeepers. If you buy a modern clock or watch the chances are that it will contain a thin sliver of quartz which will maintain and control its accuracy.

Besides the crystalline quartzes there are the micro-crystalline varieties, which are known as the chalcedonies. Of these agate is the best known, together with the impure and colourful jaspers.

Citrine

Crystalline quartz sometimes contains small quantities of alien substances which have not yet been identified for certain. One of these colours the quartz to produce the purple amethyst, and another produces the yellow citrine. Some confusion has been created over this stone because in the past it was sold as ‘quartz-topaz‘ or just ‘topaz‘. Topaz is, in fact, an entirely different mineral. Apart from the fact that both are yellow, citrine and topaz have nothing in common. Topaz is harder and more lustrous, and at its best a far more beautiful and expensive gemstone.

Citrine is relatively rare but a long time ago it was discovered that it was possible to transform poor-coloured amethyst crystals into attractive yellow ones by burning them. In Brazil one sees the miners heaping up piles of amethyst crystals, covering the heap with brushwood, setting light to it and in this primitive oven cooking up citrines of a richer, more attractive colour than most of those found in nature. Happily this colour change is permanent.

Smoky quartz or cairngorm

The smoky-brown form of quartz, called cairngorm in Britain because it can be found in the Cairngorm Mountains in Scotland, is also relatively rare. A lot of smoky quartz is now, however, coming out of the East. The Koreans have apparently discovered that they can produce this attractive stone from very poor amethysts by bombarding them, presumably in a cyclotron. Unlike some stones which owe their colour to radiation, these do not fade when exposed to light. As a result you can now enjoy an attractive and once relativel_yrare stone and buy it for a price substantially lower than yo_uwould have paid a few years ago, something quite unusual these days.

Green and rose quartz

One sometimes comes across transparent crystals of green quartz; this colour has also been produced by heat-treating amethyst, but these green quartz are usually rather pale and lifeless and therefore not in great demand. Very occasionally faceted pink quartz is cut from crystalline rose quartz. Most of the rose quartz which is discovered is in the form of lumps of tiny compounded crystals, however. It is translucent and full of inclusions and only suitable for carving or for making beads - very attractive beads, it must be said.

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The Quartz Family