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 state had wrongly invaded Chinese national waters and had fired upon the PLA first. Because the communists (and later the People's Republic of China) did not acknowledge any treaties between the previous Chinese government and the British, they insisted that it was illegal for "Amethyst" to cruise in the Yangtze river. On 30 July 1949 "Amethyst" slipped her chain and headed downriver in the dark, beginning a dash for freedom running the gauntlet of guns on both banks of the river. She followed the passenger ship "Kiang Ling Liberation" in the hope that the observers ashore would be confused and