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) kept "Amethyst" from joining the action. The British brought "Dédaigneuse" into Royal Navy service as HMS "Dedaigneuse". Later on 28 January "Sirius" and "Amethyst" captured the Spanish Letter of Marque "Charlotta" (or "Carlotta") of Ferol, 16 hours out of Ferol on her way to Curaçao. The capture took place about six or seven leagues from Cape Belem in Galicia. The hired armed cutter "Earl St Vincent" shared in the capture. The next day captured the Spanish privateer "Intrepido Cid". "Amethyst" and "Sirius" shared in the prize money by agreement. On 16 March, "Amethyst" encountered and captured "Nostra Signora del Carmen",