From the Greek "a-methystos," meaning "not drunk." In ancient times, it was believed that amethyst warded off drunkenness. Amethyst cups were sometimes carved. At the same time, it is said that the color of the red wine drunk from these cups was roughly the same as that of the cups themselves.

Amethyst is a variety of quartz with colors ranging from purple to violet, which owes its color to gamma radiation and the presence of trace amounts of iron in its crystal lattice.

Depending on its origin, the color of amethyst is distributed unevenly within individual crystals, and in geodes, the color is often more intense in the growth zones beneath the rhombohedral faces (at the tips). Occasionally, the color is more intense beneath the rhombohedral faces, giving the crystal a swirl-like appearance when viewed from above. In prismatic crystals, the color may appear in thin, ghost-like layers, while in scepter crystals and skeletal quartz, the color is typically concentrated along the edges and accompanied by smoky zones. Despite its intense color, the iron content occupying Si (silicon) sites in amethyst is quite low, ranging from 10 to 100 ppm.

When heated to more than approximately 300–400 °C, amethyst loses its purple color and often turns yellow, orange, or brown, coming to resemble the citrine variety of quartz. However, depending on the location and temperature during heat treatment, it can also become colorless or—rarely—green.