Green amethyst is extremely uncommon. Only certain amethyst stones from mines with a higher iron mineral content in the amethyst will produce the green color change. More often, the natural amethyst is heat treated to produce the green color.
A favorite material of ancient cultures, amethyst has endured the ages as one of man's most prized possessions. In the Middle Ages it was believed that amethyst would protect one from drunkenness. Today, some believe that amethyst has calming and protective qualities and that wearing amethyst will increase inspiration and intuition.