PLAY-OF-COLOR

Photo courtesy of Scott Papper, GIA GG, AJP, CMA (NAJA), Global Gemology & Appraisals

Some opals, but not all, possess a phenomenal property known as play-of-color.

Opals are made up of submicroscopic spheres stacked in a grid-like pattern.  As light passes between the spheres, the lightwaves bend, breaking up into different spectral colors.