amethyst [Gr.,=non-drunkenness], variety of quartz, violet to purple in color, used as a gem. It is the most highly valued of the semiprecious quartzes. It is associated with a number of superstitions, being regarded as a love charm, as a potent influence in improving sleep, and as a protection against thieves and drunkenness. Brazil, Uruguay, Sri Lanka, Siberia, and parts of North America are important sources of supply. The so-called Oriental amethyst, or purple sapphire, is not quartz but a variety of corundum, a much harder and rarer stone.