Topaz is a gemstone of all colors, and its most valuable color is a golden orange-yellow, called "imperial topaz". Topaz is commonly thought of as a sky-blue gem, but it was not until this century that blue topaz became widespread on the gem market. Natural blue topaz with a deep hue is very uncommon in nature; colorless to light hued stones are heat-treated to achieve the blue color. Likewise, topaz rarely occurs naturally in pink; virtually all pink topaz is heat treated from yellow or brownish material.

Some topaz from Russian localities are notorious for fading upon prolonged exposure to light. Stones from these localities are undesirable as gems. One should always inquire about the origin of the topaz before buying it to make sure it will not fade.

Care and caution must be exercised with topaz gems, for its perfect cleavage may cause it to chip or form internal flaws if hit too hard. Topaz cutting also requires special practice for this reason.

USES
Topaz of all different colors are used in jewelry. The orange, pink, and blue colors are most often cut for gems, and colorless topaz is sometimes cut with the brilliant cut, resembling diamond. Topaz is sometimes found as enormous flawless crystals, and some gigantic gems and faceted spheres have been formed from them, making unique and exquisite gem pieces. Topaz is rarely cut into cabochons.

VARIETIES
On the gem market, topaz is usually classified by color. Below is a list of the color names designated for gem topaz:

Pink Topaz
Blue Topaz
Brown Topaz
Green Topaz