iridescentes

Iridescence is a color phenomenon in which a surface appears to change hue as the angle of light or the observer shifts. Objects described as iridescent or iridescentes exhibit this color-shifting effect primarily due to structural coloration rather than pigments.

The effect arises from light interacting with micro- or nano-scale structures. Thin-film interference occurs when light reflects from multiple layers, producing constructive and destructive interference that favors certain wavelengths at particular angles. Multilayer stacks, diffraction from regular nanostructures, and photonic-crystal-like arrangements can all produce vivid, angle-dependent colors. In nature, surfaces often combine several mechanisms, and the observed colors can depend on lighting, viewing angle, and polarization.

Nature provides many iridescent examples. Butterfly wings and moth scales, especially those of Morpho species, display bright, changing blues and greens. Peacock and other birds show iridescent feathers created by microscopic barbules. Jewel beetles and other insects have iridescent elytra, while some shells exhibit nacre, whose layered structure creates a lustrous, color-shifting surface. Opals show a related phenomenon known as play of color, caused by diffraction within silica spheres.

In human-made materials, iridescence appears in coatings, holographic films, and security features on banknotes. It also inspires biomimicry in textiles, cosmetics, and architectural finishes, where angle-dependent color offers dynamic visual effects. Because iridescence depends on viewing geometry, a single fixed color is not always representative, giving iridescent surfaces a distinctive, shifting appearance.