Amethyst is a variety of quartz that's said to have many special power and qualities all throughout history... worn by king and queens throughout history.
It's said that amethyst protects against disease, helps the wounded, clams the passions, and boosts intelligence and shrewdness... also controls evil thoughts and dispels demons.
In Tibet rosaries are often made with amethyst because it is considered to be sacred.
Amethyst is also one of the 12 stones on the breastplate of the high priests of Yahweh as mentioned in the bible. Symbolizing piety, amethyst was used for the ornamentation of churches in the Middle Ages, and especially Catholic churches. In fact, bishops still often wear amethyst rings.