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 to lose her pursuer at 00:24 on 13 April by making a sharp turn. At 01:27 hrs, Kölle ordered his engines stopped to try to ascertain where "Empire Amethyst" was. Kölle decided to head in the direction that "Empire Amethyst" was generally heading and by 04:30 had found her again. At 05:52, Kölle aimed the first of two torpedoes at "Empire Amethyst", which hit under the bridge. The second exploded forward of the engine room and she exploded in a mass of flames that were visible from away. "Empire Amethyst" sank with the loss of all 47 crew at .