IGL

Topaz

Topaz Overview

Definition Value
Chemical Formula Al2SiO4(F,OH)2
Color White, Colorless, Blue, Red, Green, Yellow, Orange, Brown, Pink, Purple, Gray, Multicolored
Hardness 8
Crystal System Orthorhombic
Refractive Index 1.610 - 1.638
SG 3.4 - 3.6
Cleavage 1,3 - basal
Sapphire is the most precious and valuable blue gemstone. It is a very desirable gemstone due to its excellent color, hardness, durability, and luster. In the gem trade, Sapphire without any color prefix refers to the blue variety of the mineral Corundum. However, the term Sapphire encompasses all other gem varieties and colors of Corundum as well, excluding Ruby, the red variety of Corundum, which has its own name since antiquity.


Topaz About

Topaz is a fairly common and inexpensive gemstone. It can be found in huge and flawless crystals, which can be faceted into giant gemstones which can weigh thousands of carats. Some of the largest gemstone pieces ever cut were of Topaz. Topaz is a hard and durable gemstone, and will not dissolve in most chemical solvents. However, it does have perfect cleavage which can make it prone to chipping or forming flaws if banged hard. Topaz is also a pleochroic gemstone and can have varied color intensity when viewed at different angles. Due to its good cleavage and pleocroic nature, care must be exercised when faceting Topaz gemstones. Blue Topaz does occur in nature, but is rare and almost always lightly color. Most if not all blue Topaz used in jewelry has been irradiated and heat treated to artificially create the blue color. The original stones are colorless or lightly colored, and the radiation process gives them their deep sky-blue colors. In a few rare circumstances, some forms of blue Topaz tend to slightly fade in exposure to sunlight after extended periods of time.


Topaz Uses

Topaz of all different colors are used in jewelry, in rings, earrings, necklaces, pendants, and bracelets. The blue, orange, and pink colors are most often cut as gemstones, and colorless Topaz is becoming increasingly popular as an inexpensive Diamond simulant. Gigantic gems and faceted spheres are cut from huge flawless crystals, and these make exquisite and exclusive collectors items. Topaz is rarely cut into cabochons. Topaz is the traditional birthstone for November.