Color rendering, and the color rendering index of CRI is a way to measure just how well one can perceive colors from a light source in relation to a known source, such as daylight or a black background of the same color temperature. Incandescent lamps generally will have a CRI of about 100. Fluorescent tubes that are trying to replicated real life will have CRIs between 50 and 99. Under some fluorescent lights – the typical lights that you might see in an office – the skin does not look quite as pink as it does in reality, and it can give an almost sickly pallor to the skin. The CRI is going to determine just how natural – or unnatural – things look under that light.