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 go from Shanghai to Kiangyin, 40 miles down river from the "Amethyst". "Consort" reached the "Amethyst" at about three in the afternoon and was immediately fired upon. She found the fire too heavy to approach "Amethyst" and therefore passed her at speed down river. She turned two miles below and again closed "Amethyst" to take her in tow. But again she came under such heavy fire that she was obliged to abandon the attempt, although she answered the shore batteries with her full armament (including 4.5-inch (114 mm) guns) and soon signaled that she had silenced most of the opposition.