What is CRI?

CRI is a numerical representation of how accurately a light source portrays colour with a scale running from 0 to 100. A light source with a poor CRI e.g. low pressure sodium (as found in yellow streetlights) will make all colours look very similar whereas a light source with a high CRI will make greens look green, yellows look yellow and blues look blue etc. It is advisable to use CRI >80 for commercial/domestic usage and CRI>70 for industrial usage - some special applications use CRI>90 or higher. It is worth noting that the CRI number is an average taken across the colour spectrum, some "high CRI" sources have very poor response in the red part of the light spectrum but are good elsewhere. If accurate colour rendering is important to your project, it is worth checking the values across the whole spectrum.