Multichrome is a nail polish finish that uses interference pigments (mica or borosilicate flakes coated with titanium dioxide or iron oxide) that shift between three or more colours as the viewing angle changes.
Also known as: multichrome polish, colour-shift polish, colour shifting nail polish, chameleon polish
Multichrome polish uses interference pigments. Each pigment is a flake of mica or borosilicate glass coated with thin layers of titanium dioxide or iron oxide. The coating reflects some wavelengths and lets others pass, so the colour you see depends on the angle between the light, the nail and your eye. A multichrome shifts through three or more colours. A duochrome shifts between two.
Multichromes show best over a dark base. Many are sold as sheer toppers designed to be worn over black, which nail painters call undies. The black absorbs the light that passes through the flakes, so only the reflected colours show and the shift looks strongest. Over a pale base the same polish looks softer and more like a shimmer (Cirque Colors).
Cirque Colors groups its Shimmergraphic and Spotlight Shimmer polishes in this family. Multichrome flakes are also sold loose for pressing into gel. Because the pigment is a flake, brush strokes can show, and a glossy top coat makes the shift read more clearly.
Multichrome differs from holographic. A holo diffracts light into the full rainbow in a fixed order (Lab Muffin). A multichrome reflects a selected set of colours, for example green, gold and copper, and can skip the rest of the spectrum. Interference pigments are inert and are removed like any regular polish.