Amethyst element impurities), and the presence of trace elements, which result in complex crystal lattice substitutions. The hardness of the mineral is the same as quartz, thus it is suitable for use in jewelry. Amethyst occurs in primary hues from a light pinkish violet to a deep purple. Amethyst may exhibit one or both secondary hues, red and blue. The best varieties of amethyst can be found in Siberia, Sri Lanka, Brazil and the far East. The ideal grade is called "Deep Siberian" and has a primary purple hue of around 75–80%, with 15–20% blue and (depending on the light source)
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