Black opals are known for their unique play-of-color, where the stone exhibits a range of colors when viewed from different angles. This phenomenon is due to the structure of the silica spheres that make up the opal. The spheres diffract light, breaking it apart into the colors of the spectrum. The specific colors and patterns observed in a black opal depend on the size and arrangement of the silica spheres. This makes each black opal truly unique, with its own individual spectrum of colors and patterns.
