Amethyst of synthetic quartz is used. 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. On exposure to heat, the irradiation effects can be partially cancelled and amethyst generally becomes yellow or even green, and much of the citrine, cairngorm, or yellow quartz of jewelry is said to be merely "burnt amethyst". The Greek word "amethystos" may be translated as "not drunken", from Greek "a-", "not" + "methustos", "intoxicated". Amethyst was considered to be a strong antidote against drunkenness, which is why wine goblets were
Yangtse Incident: The Story of H.M.S. Amethyst refuse to do. Kerans dismisses his demands but is able to manipulate Peng into the release of the Petty Officers; meanwhile, as talks progress he has the ship patched up and its engines restored. After some subtle alterations to the ship's outline to try to disguise her, "Amethyst" slips her cable and heads downriver in the dark following a local merchant ship, which "Amethyst" uses to show the way through the shoals and distract the PLA. When the shore batteries finally notice the frigate escaping downriver, the merchantman receives the brunt of the PLA artillery and catches fire, while "Amethyst"