April 19, 2014
Topaz comes in many varied colors with natural blue topaz being so light, it appears almost clear. Treated stones can come in a variety of blues and levels of saturation. Unless a stone is colorless, the assumption should be that it was heat-treated.
Heat treating involves heating the stones at varying temperatures and lengths of time to achieve blues that range from greenish to the more valuable London blue, which has a gray tint. The stones can also be almost aqua, sky blue or electric blue.
Topaz can be cut into almost any shape and size. While the largest piece of Topaz every found, was from Brazil weighing over 6 kilograms, most Topaz found are only a few carats in size.