Amethyst and it can not be differentiated with absolute certainty without advanced gemmological testing (which is often cost-prohibitive). There is one test based on "Brazil law twinning" (a form of quartz twinning where right and left hand quartz structures are combined in a single crystal) which can be used to identify synthetic amethyst rather easily. It is possible to synthesize twinned amethyst, but this type is not available in large quantities in the market. Single-crystal quartz is very desirable in the industry, particularly for keeping the regular vibrations necessary for quartz movements in watches and clocks, which is where a lot
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