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Jewelry News11/28/2009 Refer a FriendStore Information |
 Tourmaline shows the widest range of lovely colors of all gemstones. Every possible hue can be found in every degree of saturation in this most versatile of all gems; besides which there are parti-colored stones where the color changes sharply or gradually from one end to the other or where two or more colors are arranged concentrically or in a multitude of parallel stripes. There are also somewhat coarsely grained cat's-eyes in all colors.The name 'tourmaline' comes from a Sinhalese root meaning 'a colored stone' and least confusion is caused by using it with with an appropriate prefix when referring to the various colors, as brown tourmaline and blue tourmaline, for example. It is not surprising, however, that so polychromatic a species should have become endowed with a large number of variety names. Thus we have achrolite for the colorless variety (the word means 'colorless' in Greek);dravite (after a Russian river) for brown colors; rubbelite (dangerously suggestive of ruby) for the pink and red varieties; indicolite for blue; siberite for violet; and schorl for black, a stone formerly much used in mourning jewelry. There are also some wholly misleading names, such as 'Brazilian emerald' for green stones, which are best forgotten quickly. Tourmaline is fairly hard gemstone which can be worn in any form of jewelry. Fully transparent stones were formerly fashioned in the mixed cut (brilliant cut crown, step cut pavilion); now a simple step cut is more usual. Cloudy stones are made into cabochons or beads. The stone is very popular in many countries and in China was worn to indicate mandarin rank. It was also carved, sometimes quite elaborately, as pendants, buttons, tiny bowls, and 'fingering pieces' which were passed across the fingertips to soothe the nerves. Advantage was clearly taken of any parti-coloration present in a stone to introduce different colors into the carved design. In the western world the most valuable colors are clear ruby red and a bright sapphire blue, followed by parti-colored stones and bright greens. The duller greens and browns are rather more common. Outstanding optical attributes of tourmaline are its marked birefringence and its strong dichroism. In most stones a light and dark tint of the main body color are present and the stones can accordingly be cut so as to present either a lighter or a darker shade. Another characteristic property of tourmaline is its pyro-electricity. When heated, or even rubbed hard with a cloth, it acquires an electric charge, positive at one end and negative at the other, and will attract such items as ashes and small scraps of paper. As with quartz, specimens of high purity can be used to control oscillations. Although tourmaline has been gathered in the East for centuries, in Burma, Thailand and particularly in Ceylon, it does not seem to be have been imported from Europe much before the eighteen century and there is no obvious mention of it in antiquity. Now more tourmaline is mined in Minas Gerais in Brazil. Excellent material also comes from California; other localities are in Maine and Connecticut. Malagasy has rich deposits of gem-quality tourmalines in every color; fine green, pink and blue stones come from Russia; Tanzania has increased its production. In Europe, a little tourmaline comes from Switzerland. The stone is not synthesized commercially. 
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