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) company with , captured "Agnela". On 30 July "Amethyst" captured the "Ebenezer", and then on 1 August "Amethyst" captured "Juno". In December "Amethyst" participated in the pursuit of a French squadron under Admiral Willaumez. In November 1805 "Amethyst" encountered the brig-sloop off the coast of Madeira. After a series of ambiguous and misinterpreted moves by the other, the two captains mistook each other for enemies and opened fire. Both vessels survived and the two captains proceeded to exchange mutually recriminatory letters. "Amethyst" was among the vessels that shared in the proceeds of the capture, on 25 July 1805, of the