Topaz is found colorless, bluish, yellow, pink, orange, brown and greenish in color. It is commonly found in pegmatites and rhyolites. The most famous variety is orange to pink imperial topaz from Brazil. Blue topaz (Swiss Blue topaz and London Blue topaz) is commonly treated using irradiation to achieve the color. Mines are found in Afghanistan, Brazil, Burma, Madagascar, Pakistan, Russia, Sri Lanka and Ukraine.