Metamerism

Take two different colored surfaces: they can appear to have exactly the same “color” under daylight natural illumination for instance, and appear to have different colors when illuminated by an incandescent or fluorescent light bulb. This means that distinct spectral compositions incident onto the eye can induce the same color perception: this is called metamerism.

Two different diffuse reflection spectra may then appear to be visually identical under a given condition of illumination, and be visually different under other illumination conditions. This may occur when pigments or dyes used to give the color to an object are not the same. This may also occur when a given pigment is coated onto different substrate materials, as it is the case for instance in colored car bodies when metallic, plastic or synthetic resin pieces are used.

Metamerism is mostly seen for dark blue or green, as well as for brown.