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
Yangtse Incident: The Story of H.M.S. Amethyst refuse to do. Kerans dismisses his demands but is able to manipulate Peng into the release of the Petty Officers; meanwhile, as talks progress he has the ship patched up and its engines restored. After some subtle alterations to the ship's outline to try to disguise her, "Amethyst" slips her cable and heads downriver in the dark following a local merchant ship, which "Amethyst" uses to show the way through the shoals and distract the PLA. When the shore batteries finally notice the frigate escaping downriver, the merchantman receives the brunt of the PLA artillery and catches fire, while "Amethyst"