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
HMS Amethyst (F116) took place in the North Atlantic, south of Waterford and resulted in the loss of all 49 of the U-boat's crew. During the war the "Amethyst" was credited, along with the sloops , , , and frigate , with sinking the in the North Channel on 16 January 1945. The British Admiralty withdrew this credit in a post-war reassessment. On 20 April 1949, "Amethyst" was on her way from Shanghai to Nanking (now Nanjing) when she was fired upon by the People's Liberation Army, thus starting the Amethyst Incident. "Amethyst" was trapped in China until 30 July 1949 when she