Amethyst is not primarily defined by carat weight; this is different to most gemstones where the carat weight exponentially increases the value of the stone. The biggest factor in the value of amethyst is the color displayed. The highest grade amethyst (called "Deep Russian") is exceptionally rare and therefore, when one is found, its value is dependent on the demand of collectors. It is, however, still orders of magnitude lower than the highest grade sapphires or rubies (padparadscha sapphire or "pigeon's blood" ruby). Amethyst Amethyst is a violet variety of quartz. The name comes from the Koine Greek ἀμέθυστος "amethystos" from
HMS Amethyst (1903) HMS Amethyst (1903) HMS "Amethyst" was a third-class protected cruiser of the "Topaze" class of the Royal Navy. She was launched in 1903, served during World War I at the Dardanelles and Gallipoli, in the Mediterranean and the South Atlantic. She was sold for scrap in 1920. She was laid down in January 1903 at Armstrong, Elswick, was launched on 5 November 1903 and was completed in March 1905. Until "Amethyst" was built, the largest warships fitted with steam turbines were destroyers. Their use in "Amethyst" reduced overall range at 10 knots by , but increased it by at 20