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
SS Empire Amethyst at Belfast to allow a crew member to be discharged through illness and a replacement to be taken on board. On reaching Freetown, "Empire Amethyst" sailed for New Orleans. In mid-April 1942, "Empire Amethyst" left New Orleans bound for Freetown carrying a cargo of 12,000 tons of motor spirit. Her intended route took her via the Lesser Antilles and then across the Atlantic to Freetown. "Empire Amethyst" was spotted by the crew of on 12 April 1942. The U-boat captain, Walther Kölle, believed that she was being escorted by and did not attack. At 03:02 hrs "Empire Amethyst" received a