Topaz is commonly thought of as a sky-blue gem, but it was not until this century that blue topaz became widespread on the gem market. Natural blue topaz with a deep hue is very uncommon in nature; colorless to light hued stones are heat-treated to achieve the blue color. Likewise, topaz rarely occurs naturally in pink; virtually all pink topaz is heat treated from yellow or brownish material.

Some topaz from Russian localities are notorious for fading upon prolonged exposure to light. Stones from these localities are undesirable as gems. One should always inquire about the origin of the topaz before buying it to make sure it will not fade. Care and caution must be exercised with topaz gems, for its perfect cleavage may cause it to chip or form internal flaws if hit too hard.