[2][3][4] The irradiation causes the iron Fe3+ ions that replace Si in the lattice to lose an electron and form a [FeO4]0 color center.

[10][11]The color of amethyst has been demonstrated to result from substitution by irradiation of trivalent iron (Fe3+) for silicon in the structure,[4][12] in the presence of trace elements of large ionic radius,[3] and to a certain extent, the amethyst color can naturally result from displacement of transition elements even if the iron concentration is low.

Between 2000 and 2010, the greatest production was from Marabá and Pau d'Arco, Pará, and the Paraná Basin, Rio Grande do Sul, Brazil; Sandoval, Santa Cruz, Bolivia; Artigas, Uruguay; Kalomo, Zambia; and Thunder Bay, Ontario.

Lesser amounts are found in many other locations in Africa, Brazil, Spain, Argentina, Russia, Afghanistan, South Korea, Mexico, and the United States.

[14] Amethyst is produced in abundance in the state of Rio Grande do Sul in Brazil where it occurs in large geodes within volcanic rocks.

[19] The large opencast amethyst vein at Maissau, Lower Austria, was historically important,[1] but is no longer included among significant producers.

[14] Much fine amethyst comes from Russia, especially near Mursinka in the Ekaterinburg district, where it occurs in drusy cavities in granitic rocks.

[14] Smaller occurrences have been reported in the Red Feather Lakes, near Fort Collins, Colorado; Amethyst Mountain, Texas; Yellowstone National Park; Delaware County, Pennsylvania; Haywood County, North Carolina; Deer Hill and Stow, Maine, and in the Lake Superior region of Minnesota, Wisconsin, and Michigan.

[25] Anglican bishops wear an episcopal ring often set with an amethyst, an allusion to the description of the Apostles as "not drunk" at Pentecost in Acts 2:15.

[1] Synthetic (laboratory-grown) amethyst is produced by a synthesis method called hydrothermal growth, which grows the crystals inside a high-pressure autoclave.

Its chemical and physical properties are the same as those of natural amethyst, and it cannot be differentiated with absolute certainty without advanced gemmological testing (which is often cost-prohibitive).

[7] Treated amethyst is produced by gamma ray, X-ray, or electron-beam irradiation of clear quartz (rock crystal), which has been first doped with ferric impurities.

Humbled by Amethyste's desire to remain chaste, Bacchus poured wine over the stone as an offering, dyeing the crystals purple.

Her life was spared by Artemis, who transformed the maiden into a statue of pure crystalline quartz to protect her from the brutal claws.

However, the goddess Rhea does present Dionysus with an amethyst stone to preserve the wine-drinker's sanity in historical text.

[38] Until the 18th century, amethyst was included in the cardinal, or most valuable, gemstones (along with diamond, sapphire, ruby, and emerald), but since the discovery of extensive deposits in locations such as Brazil, it has lost most of its value.

When one is found, its value is dependent on the demand of collectors; however, the highest-grade sapphires or rubies are still orders of magnitude more expensive than amethyst.