Topaz is named from Greek 'topazion' for a type of gemstone, probably after Sanskrit 'tapas' - fire, alluding to the brilliance of gem-quality material. Topaz has been known from antiquity.
Blue Topaz does occur in nature, but is rare and almost always light color. Colorless or lightly colored topaz goes through processes that create the blue color. Among the colours thus created, lighter blue are known as Sky Blue topaz.
Irradiation followed by heat-treatment produces most blue colors. Irradiation also produces yellow, orange, red, brownish, pinkish and greenish colors: often unstable, may fade upon direct exposure to sunlight. Coated entirely or partially: may show peeled coating at facet junctions, iridescence (reflecting light), spotty coloration. Some surface-treatments are removed only with acids (mostly green and blue) - Blue Chart Gem Identification, Herve Nicolas Lazzarelli, 2010, p 5
Significant Gem Localities:-
Mined in Brazil, Pakistan, Afghanistan, India, China, Burma, Sri Lanka, Japan, Russia, Ukraine, Australia, Madagascar, Namibia, Nigeria, Zimbabwe, Mexico, U.S.
Hardness of 8