Peridot is August's birthstone and the 15th anniversary gemstone. Peridot can be pure grass green to a yellowish-green. In history it has been confused with emeralds like the 200-ct. gems adorning the shrine of the Three Holy King's in Germany's Cologne Cathedral. Or even Cleopatra's famous emerald collection might actually have been peridot according to some historians. Peridot was mined by the ancient Egyptians on the Red Sea island of Zabargad. They called it the "gem of the sun." Some Peridot is found in meteorites but most peridot used in jewelry was formed deep inside the earth and was delivered to the surface by volcanoes. Peridot is mined in Myanmar or the Himalayas but also here in the United States in Arizona. In 2005, Peridot was found in comet dust brought back from the Stardust robotic space probe.