Cat's eye is a unique gemstone known for its striking optical phenomenon called chatoyancy, which resembles the slit-like pupil of a cat's eye. This effect occurs when light reflects off parallel inclusions within the stone, creating a bright line that moves across its surface as the gem is turned. Commonly found in chrysoberyl, cat's eye can also occur in other minerals like tourmaline and quartz. The gemstone is often used in jewelry, particularly in rings and pendants, due to its captivating appearance. Cat's eye is believed to possess protective qualities and is associated with good fortune in various cultures. Its rarity and distinctive look make it a sought-after choice for collectors and enthusiasts alike.