Amethyst element impurities), and the presence of trace elements, which result in complex crystal lattice substitutions. The hardness of the mineral is the same as quartz, thus it is suitable for use in jewelry. Amethyst occurs in primary hues from a light pinkish violet to a deep purple. Amethyst may exhibit one or both secondary hues, red and blue. The best varieties of amethyst can be found in Siberia, Sri Lanka, Brazil and the far East. The ideal grade is called "Deep Siberian" and has a primary purple hue of around 75–80%, with 15–20% blue and (depending on the light source)
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