The Color Rendering Index (CRI) is a measure of how well colors are rendered by the light. A CRI of 100 would mean the colors look identical to how they look under tungsten light. The lower the CRI the less true to life the colors appear, especially skin tones. Some fluorescent tube lights have a CRI of around 70, resulting in skin tones that appear dull and even a little greenish. A light with a CRI of 90+ is considered good, really good lights are 96+.