The holographic effect of nail polish creates a rainbow glow on the nail surface that changes depending on the angle of incident light and movement. This appearance is achieved with special pigments containing microscopic particles. These particles act as miniature prisms that break down the light into its colour spectrum, similar to a rainbow in the sky or a glow on the surface of a CD. The effect is best seen in direct sunlight or under strong artificial lighting. There are two basic types. A linear holographic effect, referred to as a "holo", produces a distinct and continuous rainbow stripe. On the other hand, a diffuse holographic effect has particles more randomly distributed and manifests as a more subtle iridescence across the entire surface of the nail.