This is interesting...

Amethyst is a variety of'(quartz which occurs in a transparent light to dark purple. It has long been treasured by kings and queens as well as high figures in religious sects because of its rich, royal color can be traced back to the Minoan period in Greece (c. 2500 B.C.) when it was found as polished cabochons (dome-shaped stones) set in gold. It is represented in many artistic eras since then.