Amethyst is the official birthstone for February as adopted by the American National Association of Jewelers in 1912. It is also the birth stone for the Zodiac sign of Pisces. See the birthstone table for additional references to this stone on alternative birthstone charts. Amethyst is suggested as a gem to give on the 4th, 6th and 17th wedding anniversaries.

Amethyst is the purple variety of quartz and the most valued member of the quartz family. It must be purple to be amethyst, but it can display a range of shades including deep purple, light lilac, lavender and mauve. Top quality amethyst is a deep medium purple with rose-colored flashes. Its purple color made it a stone of royalty for many thousands of years. See note about incorrectly named "green amethyst".

Amethyst can occur as crystals that are six sided on either end. It also forms as drusy which are crystalline crusts covering the host rock. It is found inside geodes and in alluvial deposits all around the world and occurs in both crystalline or massive forms. When manganese is present in clear quartz amethyst is produced, while the amount of iron contained in the specimen accounts for the depth of purple.

Mohs scale of hardness is 7.

Most amethyst gemstones on the market today are heat-treated to produce a deeper color. Heat treating is permanent and these stones will not fade over time. Unless otherwise stated, assume that any amethyst you purchase today has been heat treated to increase the depth of color. Also, note that most citrine available on the market today is actually heat treated amethyst.