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 (1799) American brig "Rising Sun". On 10 March 1808 "Amethyst" captured the Spanish brig "Vigilantie". Eleven days later "Amethyst" recaptured the Portuguese schooner "Inseperavil Unio". On 3 May "Amethyst" and captured the French sloop "Actif". Sixteen days later, "Amethyst", "Conflict", and were in company when they captured the French schooner "Annais". The next month, on 10 June, "Amethyst" and "Conflict" captured the Spanish schooner "Carmelita". Fourteen days later, "Amethyst" captured the American brig "Sally Tracey". Then "Amethyst" was again in company with "Growler" when they captured "St. Etienne", "Maria Julia", and six chasse marees on 9 July. Lastly, on 17 September