Amethyst is a purple-colored quartz, and was once considered to be in the same category as diamonds, sapphires, rubies, and emeralds. It has a chemical composition of SiO2, a trigonal crystal system, and (among other ways) it obtains its color from substitution by irradiation of trivalent iron Fe3+ for silicon. Amethyst is also the birthstone for February! Lavender Stone Jewelry Gift, Faceted Mineral Crystal Necklace Gift, Faceted Crystal Necklace For Gifts, Faceted Amethyst Spiritual Gemstone, Quartz Gemstone Pendant Crystal Necklace, Quartz Crystal Pendant Necklace With Gemstone, Purple Amethyst Pendant Crystal Necklace, Purple Amethyst Necklace With Raw Stone, Amethyst Birthstone Pendant Crystal Necklace