pearlescence

Pearlescence is an optical phenomenon in which a surface displays a soft, pearly luster with subtle color play when viewed from different angles. The effect arises from light interacting with microscopic surface structures that cause interference and scattering.

Natural occurrences are most notable in nacre, the iridescent material lining many mollusk shells, and in pearls themselves. Nacre's layered calcium carbonate platelets reflect light to produce a pearly sheen. Some minerals are described as having a nacreous or pearlescent luster in mineral classifications.

The mechanism involves thin-film interference and scattering by organized microstructures. Observed color and intensity shift with the viewing angle, yielding a diffuse, non-metallic iridescence rather than a sharp rainbow.

Artificial pearlescent materials are widely used in paints, coatings, plastics, cosmetics, and ceramics. Mica flakes coated with metal oxides create interference pigments that imitate nacre, delivering a shimmering, color-shifting finish.

Pearlescence is related to but distinct from opalescence and iridescence. Opalescence comes from scattering in disordered structures, giving milky colors; iridescence refers to broader, angle-dependent color shifts. In mineralogy, nacreous luster is a form of pearlescence linked to nacre.