Cat's Eye or Chatoyance is a visible phenomenon in which a gathering of reflected light, which is known as a ""cat's-eye,"" runs just beneath the surface of a cabochon-cut gemstone. Chrysoberyl and tiger's-eye are two of the most popular known gem materials that manifest this phenomenon. Magnificent specimens of chrysoberyl exhibit the finest chatoyance and the tiger's-eye is the chatoyant gem most extensively used in jewelry. Chatoyance occurs in stones that contain a great number of very thin parallel compositions within the stone, identified as a ""silk."" The light bounces from these embodiments to form a thin band across the surface of the stone. The collection of light always occurs at right angles to the length of the parallel formations. These inclusions can be crystals, vibrating tubes, or other elongated structures that are existing throughout the stone and are usually joined with a crystallographic axis. Needle-like crystals of rutile and hematite are well-known for providing a cat’s-eye in many individuals.