Topaz is one of the most popular and widespread jewelry stones, it is beautiful and has many colors and shades. However natural topaz is almost always colorless or has a light blue shade. Modern technologies allow obtaining yellow, brown, orange, light and dark blue colors of topaz when the stone is irradiated with neutrons and (or) electrons and gamma radiation. Interestingly, all-natural colored raw topaz stones are a product of natural radiation. The main color centers in topaz are always radiation defects. Only pink topaz is an exception because it is colored pink by radiation color centers, which contain chromium or manganese atoms.
Thus all topaz on the market is the product of radiation exposure either in the laboratory or nature. 99% of the stones are technically processed in the laboratory to get their color. Blue topaz is the most popular and is in great demand in many countries.