time：2015/09/10 Gem Type view：596
Topaz of any type is an important jewelry stone due to its hardness (8 on the Mohs scale) and high refractive index.
Topaz comes in many colors, including clear, brown, yellow, orange, red, pink and blue. The blue topaz, with a pale to medium blue color created by irradiation can be found in very large sizes at affordable prices. The fine golden-yellow variety, known as Imperial Topaz, is relatively scarce.