Opals can be divided into many groupings. We make jewelry with many different types of Opals and I will talk all about all of those types. The first division or groupings addresses the Phenomenal Opals or Precious Opals from Common Opals. The Phenomena that Opals display is called Play of Color. The Play of Color is a result of light going into the crystal and reflecting back out. As the reflected light leaves the opal, there is light dispersion which separates the light into a spectral division or rainbow effect, also called diffraction and interference patterns. Opal consists of varying layers of silica spheres that are not always uniform which result in the Play of Color. Precious Opals have Play of Color, Common Opals do not have Play of Color.