Peridot is August's birthstone. This gem has been mined for thousands of years, is mentioned in the bible, and was apparently a favourite of Cleopatra's! Peridot is one of the few gemstones that occur in only one colour: green. The intensity and tint of the green, however, depends on the percentage of iron that is contained in the crystal structure, so the colour of individual peridot gems can vary from olive, to lime, to brownish-green.  Peridot is considered a very joyful, warm, friendly stone that can ease anger and jealousy, as well as encouraging open-heartedness.