CRI

A Colour Rendering Index (CRI) is a quantitative measure of the ability of a light source to reveal the colours of various objects faithfully in comparison with an ideal or natural light source. 

The index is measured from 0-100, with a perfect 100 indicating that colours under the light source appear the same as they would under natural sunlight.

A low CRI indicates than objects may appear unnatural under the source, while a light with a high CRI rating will allow an object's colours to appear more natural.