Moonstone is a beautiful gemstone that diffracts light and creates an iridescence that is almost Opal-like.  It's known among metaphysical believers to strengthen feminine energy, provide clarity of perception and intuition, and to help calm and protect during sleep.  Moonstone is considered to be a birthstone for the month of June and is associated with the Zodiac signs of Cancer and Scorpio.  Moonstone is also aligned with the Third Eye chakra or Ajna.