August: Peridot is conventionally the stone for the sixteeth year of marriage. It is a bright lime-green stone, with no brown tinge. Pirates favoured it and made amulets set with peridot to protect themselves against evil. Set in gold, it blocked the terrors of the night. Peridot, also known as chrysolite or olivine, was credited with the power of prophecy and those who wore it became gracious and loving.