Structural Color

The traditional type of color, as most people understand it, is based on pigmentation. Pigments achieve their color through absorbing and reflecting different wavelengths at different levels. Structural pigmentation takes a different approach. Different wavelengths are diffracted/reflected at different angles.

In its simplest form, this essentially separates white light into a rainbow. Simple (one-layer) structural color will look different depending on the viewing angle (Iridescence). More complex forms of structural color (multi-layer) uses very specifically spaced layers to reduce the effect of the viewing angle.

For example, the coloration in butterfly wings is primarily structural. Because the color is mostly independent of viewing angle (i.e. the butterfly doesn’t change colors as it flies around), we know that there is a complex structural element at play. However, there are elements of iridescence as well.