Amethyst is a variety of quartz which is found in various shades of purple; this colour is caused by natural gamma radiation and impurities of iron and aluminium; amethyst can be translucent to transparent; coloration is often uneven. In the world, there are many sites in North and South America, Asia, Africa, Russia and Germany. In the Czech Republic there, are two significant deposits – Kozákov by Turnov and Ciboušov near Klášterec nad Ohří. Amethyst may fade on exposure to light or by heating (already at 200 °C it loses its color); heating to 470-750°C causes transformation to citrine; be careful not to scratch it by harder subjects. Interesting are amethyst “geodes” that are stones with cavity inside which is partially or completely filled with crystals. Since the 70’s even synthetically produced amethyst appears on the market. Its name comes from the Greek, it could be translated as “not drunk” – it was believed that it protected against drunkenness or intoxication, therefore it was often use for making wine goblets. Historically, the purple colour was assigned to power, that is why amethyst was very important. Use of amethyst is evidenced already at 25,000 years BC, it was worn by royalty of Ancient Egypt (beads, amulets), it was used in other ancient civilizations (in Asia). Amethyst was reserved for the Roman nobility, was equally important for the Greeks, it was called “the stone of bishops”, it is part of the British crown jewels (sceptre), was favourite to Catherine the Great, it was extremely popular for making jewellery in the Victorian era. In the Czech Republic, the stone was used to decorate chapel of St. Catherine (1138 stones of mainly jasper and amethyst from the Ore mountains, with size up to 3 dm²) and St. Cross (2496 pieces of the same stones) at castle Karlstejn and in the chapel of St. Wenceslas in the St. Vitus Cathedral (coming from the Ore Mountains – mine in Ciboušov). Amethyst is part of the Czech crown jewels – the crown crucifix from the 14th century. I was popular also during the Baroque period.