Amethyst is a type of quartz that is mostly found in geodes and hollow agates. It is composed of silicon dioxide, and scores a 7 on the Mohs hardness scale. From different angles, amethyst occurs in primary hues from a light pinkish violet to a deep purple.
Tiger's Eye is a chatoyant gemstone that is usually a metamorphic rock that is a golden to red-brown color, with a silky luster. Its hardness on the Mohs scale is 5.5-6, and its specific gravity is 2.64-2.71.