What are the Characteristics of Topaz?
Topaz commonly occurs in colorless and brown colors. The precious or imperial topaz is the rare golden, orange, pink, red and purple colors that are the foundation of the fine gem market. The yellow and brown topaz owe their color to color centers. The impurity chromium produces pink to red colors and a combination of color centers and chromium produces orange topaz. While some blue topaz is found in nature, most of the material is produced by a combination of irradiation and heating treatment. The blue topaz is also colored by color centers. Topaz from most sources is reasonably clean. Consequently eye-clean stones are both desirable and possible. The exception is with pink and red topaz, where only small stones are normally available. In those colors, a slightly higher degree of inclusions are tolerated. While topaz does have a perfect basal cleavage, it is not an easy cleavage, and does not present too much difficulty to the cutter. Yet cutters will often try to ensure that no facet
