Amethyst is a purple variety of crystalline quartz. It is the world's most popular purple gemstone and has been used for thousands of years. This amethyst is tumbled from crystals that grew with zones of white quartz alternating with purple amethyst. That is the cause of the banded pattern. Some people call it "chevron amethyst" because some pieces have a "V" shaped color pattern in the shape of a chevron.
Amethyst is a February birthstone, the 17th anniversary gemstone, and the Pisces zodiac gemstone. Trivia: Amethyst is one of the precious stones referred to in the Bible.