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) escaped under cover of darkness. For the 1957 film "Yangtse Incident: The Story of HMS Amethyst", "Amethyst" was brought out of storage to play herself. As her engines were no longer operational, her sister ship, , was used for shots of the ship moving. "Amethyst" was scrapped shortly after the filming was finished. HMS Amethyst (F116) HMS "Amethyst" was a modified "Black Swan"-class sloop of the Royal Navy. She was laid down by Alexander Stephen and Sons of Linthouse, Govan Scotland on 25 March 1942, launched on 7 May 1943 and commissioned on 2 November 1943, with the pennant number