Amethyst clusters Triple-A on stand, from Uruguay

Amethyst is a violet variety of the mineral quartz (SiO₂) and is the most sought-after stone from the quartz group. Etymology The name comes from the Greek αμεθυστος (amethystos). Amethyst was already known to the Egyptians, Etruscans and Romans, and Pliny the Elder already described amethyst. Ancient China cut small gems from amethyst. In the Middle Ages, amethyst was also highly valued in Europe. It was called the bishop's stone' because it used to be a popular gemstone for church dignitaries, and it was said to have magical powers. It was the symbol of lovers, the stone of temperance, and a protector against sorcery and witchcraft. Jacob van Maerlant explains that the stone drives away drunkenness. It has been assumed that the Greek name means "against intoxication": one would not get drunk from wine drunk from a cup made of amethyst. Origin: metamorphic, hydrothermal, alluvial The crystals always grow on a substrate, but the prisms are often poorly developed; as a result, the crystal points of spit amethyst predominate, and this is where the colour is also the most intense. These parts are knocked off, that is, broken off for further use. Firing at a temperature between 470 and 750 degrees creates light yellow, reddish brown, green, or colourless varieties. There are amethysts that gradually fade in daylight. The original colour can be restored with radium radiation. Ionising radiation, in combination with iron, causes the colour. Amethyst is less attractive in artificial light. Occurrence Brazil has been mining amethyst deposits since the Middle Ages, primarily in Bahia, Minas Gerais, and Mato Grosso. Recently, the so-called ametrine, an amethyst-citrine, has been mined in Bolivia, in which the violet and yellow colours alternate, but the transition between the colours is sharply defined. Amethysts are also known in the United States, namely in Montana, Maine, Georgia and Arizona. Canada, Mexico, Bolivia, India, Myanmar, Japan, China, Korea, Sri Lanka, Zimbabwe, Congo and Australia are also important producers. In Russia, amethyst is found in the Urals, at Yakutsk, and on the Kola Peninsula, among other places. Amethysts are also found in Armenia, Germany, the Czech Republic, Slovakia, Bulgaria, Switzerland and Ireland. Amethyst only rarely forms larger, pure crystals. The British Museum has a unique cut stone of 343 carats. Other, smaller stones weigh less; they usually come from Brazil. The Smithsonian Institution in Washington, D.C., even has a 1,362-carat cut amethyst from Brazil and one from North Carolina that weighs 202.5 carats. Amethysts are often used in state jewels, such as Catherine the Great's sceptre and the British crown sceptre.