Topaz is an extremely versatile gemstone and is found in large clean crystals. The most commonly Topaz found on the market is blue since almost all Topaz has undergone irradiation treatment to change the colour.
Topaz ranges from colourless (white) to yellow, orange, red-brown, light to dark-blue, pink to red, violet and light-green. This is the reason why it can be mistaken for many other gemstones. Naturally coloured topaz gets its colour from iron and chromium; the impurities cause colour, whereas pure topaz is colourless. Most unadulterated topaz is colourless or pale blue. The most rare and valuable topaz is yellow, or pink to reddish-orange, and is known as “precious topaz”. Some yellowish-brown topaz gems can gradually fade when continually exposed to daylight. Red and violet topaz is incredibly rare.
Topaz is transparent to translucent. It exhibits high clarity with few inclusions, so topaz gemstones can be examined by the naked eye and found to be “eye clean”, which means that no imperfections can be seen. Topaz is highly prized for its brilliance and vitreous (glassy) luster.