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
Amethyst Incident if she came under fire from the shore batteries at Woosung. To achieve this she had moved up the Yangtze during the night, at action stations. Fortunately for the British, "Amethyst" was not spotted by the shore batteries and the two ships then proceeded down river until at 0715 they stood down from action stations and after clearing the river mouth arrived at the Saddle Islands at 1200 hrs to anchor and transfer much needed oil and stores. After a short stay at anchor, "Concord" lent "Amethyst" sailors to fill gaps in her ship's company and the two ships set