彩虹色或虹彩（英语：Iridescence），是一种结构色。彩虹色常见于肥皂泡、蝴蝶翅膀、贝壳等物体。

如果观测物体表面的角度改变，色彩也随之改变，这样一种光学现象就叫做虹彩现象，即彩虹色。

入射光线在进入两层或者多层半透明的结构时，会在结构内部形成多重反射光线，这些反射光线的相位移动和相互干涉作用导致某些波长频率的增强或者减弱，从而形成彩虹色。

Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear to change colour as the angle of view or the angle of illumination changes. Examples of iridescence include soap bubbles, butterfly wings and sea shells, as well as certain minerals. It is often created by structural coloration (microstructures that interfere with light).