Amethyst's a violet variety of quartz often used in jewelry. The name comes from the Ancient Greek a- ("not") and methustos ("intoxicated"), a reference to the belief that the stone protected its owner from drunkenness; the ancient Greeks and Romans wore amethyst and made drinking vessels of it in the belief that it'd prevent intoxication. Chemistry Amethyst's the violet variety of quartz; its chemical formula's SiO2. In the 20th century, the color of amethyst was attributed to the presence of… (More on Amethyst)