Saturday, October 20, 2007

Topaz

Topaz comes in many colors such as blue, yellow, pink, brown, green and
clear. Orange-red "Imperial" topaz is rare. Blue Topaz is much less
expensive than aquamarine and as such very popular. It looks beautiful in
rings, bracelets, necklaces, and pendants. Topaz looks magnificent with
almost any outfit.

Topaz is a common gemstone that has been used for centuries in jewelry. Its
golden brown to yellow color is classic but is confused with the less
valuable citrine, which is sold under the name topaz. The blue topaz that is
often confused with aquamarine is rarely natural and is produced by
irradiating and then heating clear crystals. Topaz is the November
Birthstone. Topaz crystals can reach incredible size of several houndred
pounds. Topaz can make very attractive mineral specimens due to their high
luster, nice colors and well formed and multifaceted crystals.

Topaz is a fluosilicate of aluminum, occurring in transparent yellow,
yellow-brown, orange-brown, light to almost medium red, very light to light
blue, very light green and violet colours.

Varieties - Coloured varieties, Imperial (reddish-orange), chatoyant
material (very rare).

Sources - Prime source is Brazil. Sri Lanka (blue), Mexico (mostly poor
quality, brownish-yellow), Russia, South Africa (blue), Utah, Afghanistan.

Treatments - Heat and chemical treatments.

History - The stone began to be used in Marco Polo's time (13th century).
Topaz mounted in gold and hung around the neck was believed to dispel
enchantment. When the powdered stone was put in wine, it was considered a
cure for asthma, insomnia, burns and haemorrhages. Topaz was supposed to
become obscure in contact with poison and to quench the heat of boiling
water. All these powers were believed to be increased or decreased with the
changes of the moon.

It has an easy and perfect basal cleavage and so gemstones or other fine
specimens should 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. When heated, yellow topaz often becomes reddish-pink. It can
also be irradiated, turning the stone a light and distinctive shade of 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.
The Egyptians said that topaz was colored with the golden glow of the mighty
sun god Ra. This made topaz a very powerful amulet that protected the
faithful against harm. The Romans associated topaz with Jupiter, who also is
the god of the sun. Topaz sometimes has the amber gold of fine cognac or the
blush of a peach and all the beautiful warm browns and oranges inbetween.
Some rare and exceptional topaz are pale pink to a sherry red.

Wear topaz only if you wish to be clear-sighted: legend has it that it
dispels all enchantment and helps to improve eyesight as well! The ancient
Greeks believed that it had the power to increase strength and make its
wearer invisible in times of emergency. Topaz was also said to change color
in the presence of poisoned food or drink. Its mystical curative powers
waxed and waned with the phases of the moon: it was said to cure insomnia,
asthma, and hemorrhages.

Perhaps the most famous topaz is a giant specimen set in the Portuguese
Crown, the Braganza, which was first thought to be a diamond. There is also
a beautiful topaz set in the Green Vault in Dresden, one of the world's
important gem collections.

Brown, yellow, orange, sherry, red, blue and pink topaz is found in Brazil
and Sri Lanka. Pink topaz is found in Pakistan and Russia.

Today we also have blue topaz, which has a pale to medium blue color created
by irradiation. Pale topaz which is enhanced to become blue is found in
Brazil, Sri Lanka, Nigeria, and China. In early 1998, a new type of enhanced
topaz made its appearance, the surface-enhanced topaz, with colours
described as blue to greenish-blue or emerald green.

Topaz is the birthstone for those born in the month of November.

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