Gemstone Chatoyancy and Stars: illuminating gemstone cabochons reveals rays and stars where light is scattered by microscopic parallel crystal fibers of rutile (titanium oxide) or magnetite that grow within the different mineral species. These fibers grow to be in alignment along the axes of the crystalline structure producing the illuminated rays: 6 point star (synthetic red ruby-aluminum oxide with trace chromium), 4 point star (black diopside- calcium magnesium silicate), and a simple “tiger