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 (F116) 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 U16. After the Second World War she was modified and redesignated as a frigate, and renumbered F116. During World War II, "Amethyst" was deployed mostly on anti-submarine patrols and escort duties. On 20 February 1945 she attacked and sank the U-boat with depth charges. "U-1276" had just sunk , a . The action