Color metamerism in teeth is a phenomenon that needs to be taken into account in cosmetic dentistry, when matching shades.
Teeth are made of hydroxyapatite. Composite bonding materials are made of organic resins impregnated with inorganic fillers. Porcelain and other ceramics are composed of different materials. Each of these materials has its color properties. It is not uncommon at all for a tooth restored to a shade match under one lighting situation to not match under different lighting.
If a crown or bonding material is created to match a tooth under warm fluorescent lighting, or incandescent lighting, the color metamerism properties of the restorative material can easily mean that the color will not match under a different light source, such as outdoor lighting. For best results, shade matching should be done either in the natural light from a large window with a northern exposure, or under color-correct fluorescent lighting. There are several companies that sell full-spectrum lighting. This lighting will be at a color temperature of 5500 Kelvin. The Durotest Vita-Lite is the original bulb manufactured to these specifications, but there are competing brands now that do the same thing. Matching colors under a full-spectrum light source should eliminate complications from color metamerism.