Peridot gems are the rare varieties of the mineral olivine, composed of chemicals including iron and magnesium, and are one of the only gems that come in only one color. While peridot only comes in a lime green color, the tone and intensity of this color can vary between individual gems. The green color of the birthstone comes from the composition of the mineral itself — rather than from trace impurities, as with many gems. That’s why this is one of few stones that only comes in one color, though shades may vary from yellowish-green to brownish-green, depending on how much iron is present. (American Gem Society). Ranking at a 6.5-7 on the Moh’s scale of hardness, peridot is a relatively soft gemstone, comparable to opals. Peridot has been found in lava flows in the United States, China, and Vietnam, as well as in a larger crystalline form inside specific types of formerly molten rock in regions including Finland, Pakistan, Myanmar, and the island of Zabargad