Crushed amethyst works wonderfully as an inlay material. Amethyst is a naturally-occurring variety of quartz that appears purple. The hue of amethyst can range from a pinkish-violet to a deep purple. Amethyst sits at a 7 on the Mohs hardness scale. Amethyst has been used in jewelry in ancient Egypt, Greece, and Rome showing that it brings a timeless beauty to any piece.