The rainbow effect inside or on the surface of a material produced by light interference or diffraction from thin films of gas, liquids or solids. This is often manifested by the appearance of color change in the object when the angle of viewing is altered. Iridescence is used in the description of pearls and mother-of-pearl.
This Shell is Exhibiting Classic Iridescence.
Iridescence Causes Beautiful Colors on Ammolites.