Topaz
An Overview of Blue Topaz
By Rajesh Kumar, Section Topaz
Posted on Tue Jul 15, 2008 at 11:54:24 PM EST
Topaz is a silicate mineral of aluminium and fluorine with the chemical formula Al2SiO4(F,OH)2. It crystallizes in the orthorhombic group and its crystals are mostly prismatic terminated by pyramidal and other faces, the basal pinacoid often being present. It has an easy and perfect basal cleavage, meaning that gemstones or other fine specimens have to be handled with care to avoid developing cleavage flaws. The fracture is conchoidal to uneven. Topaz has a hardness of 8, a specific gravity of 3.4-3.6, and a vitreous luster. Pure topaz is transparent but is usually tinted by impurities; typical topaz is wine or straw-yellow. They may also be white, gray, green, blue, pink or reddish-yellow and transparent or translucent.
Treatments
When heated, yellow topaz often becomes reddish-pink. The color change upon heating was first discovered by a Parisian jeweler around 1750. In particular the yellow Topaz of Brazil has been known to be treated frequently, by wrapping Topaz in Asbestos. Only stones of a brown-yellow color yield the pink; the pale yellow ones usually turn white. The pink color is stable. [1]. Topaz can also be irradiated, turning the stone blue, ranging from a light pure color to very dark almost electric blue. A recent trend in jewelry is the manufacture of topaz specimens that display iridescent colors, by applying a thin layer of titanium oxide via physical vapor deposition, this stone is then sold as 'mystic topaz'.
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Topaz
By Rajesh Kumar, Section Topaz
Posted on Sat Mar 31, 2007 at 02:40:26 AM EST
It is a fluorine aluminium silicate and comes in yellow, yellow-brown, honey-yellow, flax, brown, green, blue, light blue, red and pink ... and sometimes it has no colour at all. The topaz.
The topaz has been known for at least 2000 years and is one of the gemstones which form the foundations of the twelve gates to the Holy City of the New Jerusalem. These so-called apocalyptic stones are intended to serve in protection against enemies and as a symbol of beauty and splendour. It cannot be proved conclusively whether the name of the topaz comes from the Sanskrit or the Greek, though the Greek name 'topazos' means 'green gemstone'. The Romans dedicated the topaz to Jupiter.
The colour in which the topaz is most commonly found is yellow, and that is the colour in which it occurs in one of the major German gemstone rocks, the Schneckenstein (a topaz-bearing rock said to resemble a snail) in Saxony. In the 18th century, it was mined there during a period of over 60 years. However, most of the crystals were hardly a centimetre in diameter. You had to go to Siberia or Brazil to find crystals as large as your fist. Having said that, anyone who is interested can convince himself of the beauty of cut specimens in the topaz set in Dresden's Grünes Gewölbe (Green Vault). The enormous and magnificent topaz from the Portuguese crown, the Braganza, was for a long time thought to be a diamond. It weighs 1680 ct..
In mysticism, the topaz is attributed with a cooling, styptic and appetising effect. It is said to dispel sadness, anger and nocturnal fears, to warn its wearer of poisons and protect him or her from sudden death. It is reputed to make men handsome and intelligent and sterile women fertile and happy. However, it is probably better not to rely too much on its magical powers, since it was also claimed that you could immerse your hand in boiling water after a topaz had been thrown into it and retract it again unharmed! It is the stone of the month November.
In the Empire style, the topaz was still widespread, but then the more reasonably priced citrine took over from it and even usurped its name - gold topaz. Since then, the topaz has been a rather exotic figure in the jewellery trade, and has been given the additional predicate 'pure' to make it clear that the topaz, not the quartz topaz, is meant. And it is still waiting for its well deserved comeback to this day.
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