Answer:
Found in abundance, in its purest form, Amethyst is colorless. The finest quality Amethyst is medium to medium dark in tone, vivid in intensity, and purple, reddish purple to bluish purple in hue. Heating removes the color from amethyst or changes it to the yellow of citrine. Most commercial citrine is made in this manner. Amethyst is the most valuable transparent, coarse-grained variety of the silica mineral quartz that is valued as a semiprecious gem for its violet color. It contains more iron oxide Fe2O3 than any other variety of quartz, and experts believe that its color arises from its iron content. Other theories attribute the color to contained manganese or hydrocarbons. All forms of quartz (including amethyst) are piezoelectric, making for important applications in electronics. Tourmaline is the only other gemstone that possesses this property.
