Amethyst is a variety of quartz, which is defined by its purple or violet hue. This coloration results from the presence of ferric iron within the quartz structure.

The name is derived from the Greek words for "not drunken", as it was once believed that the stone could help prevent intoxication from alcohol consumption. Throughout the classical and medieval periods, the value of amethyst was actually far higher than it was today. The high price of dyes had made purple the color of emperors and kings, and the stone itself was extremely scarce. However, the subsequent discovery of an almost unlimited supply in South America pushed amethyst prices to the other extreme, and the gem is now one of the most commonly encountered and inexpensive within the marketplace.