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
Amethyst Incident Half an hour later her signals ceased, though she was making a second attempt to take the "Amethyst" in tow, having turned downstream again. This attempt also failed and she sustained further damage and casualties during which her steering was affected. She therefore had to continue downstream out of the firing area with 10 men killed and 23 wounded. "Amethyst" was re-floated just after midnight, on 21 April, after lightening the ship, and she moved up river. The Assistant British Naval Attaché, Lieutenant Commander John Kerans, joined the ship on 22 April after he had dealt with all the wounded