Topaz

Definition:

The variety of Topaz hues includes colorless, light blue, yellow, orange, pink, violet, brown and, very rarely red. The vast majority of Blue Topaz seen today is the permanent result of treating colorless topaz with irradiation and heating.

In addition, Topaz is allochromatic, which means that its color is caused by impurity elements or defects in its crystal structure rather than by an element of its basic chemical composition. The element chromium causes natural pink, red, and violet-to-purple colors in topaz. Imperfections at the atomic level in topaz crystal structure can cause yellow, brown, and blue colors. Brown is a common topaz color, and the gem is mistakenly called “smoky quartz”. Topaz is pleochroic, meaning that the gem can show different colors in different crystal directions.

Topaz actually has an exceptionally wide color range that, besides brown, includes various tones and saturations of blue, green, yellow, orange, red, pink, and purple. Colorless Topaz is plentiful, and is often treated to give it a blue color. The color varieties are often identified simply by hue name – Blue Topaz, Pink Topaz, and so forth – but there are also a couple of special trade names. Imperial Topaz is a medium reddish orange to orangey red. This is one of the gem’s most expensive colors. Sherry Topaz – named after the sherry wine – is a yellowish brown or brownish yellow to orange. Stones in this color range are often called Precious Topaz to help distinguish them from the similarly colored, but less expensive, citrine and smoky quartz. The rainbow effect seen in “Mystic Topaz” is created by coating colorless topaz with a thin artificial film.