Colour Rendering Index
CRI is the shortened form for Colour Rendering Index. CRI is a measure of how accurately an artificial light source reveals the colours of objects that it illuminates in comparison with daylight. It recently been superseded by a new, more accurate index that’s called TM-30-15 but until all manufacturers start providing this information CRI will remain important and useful.
The index runs from 0 to 100 with halogen light sources being considered as the “gold standard” with the magic CRI of 100. An example of a light source with a very low CRI is sodium street lighting where most things under them take on an odd hue and it’s virtually impossible to differentiate colours. These are often quoted as having a CRI of 20 or lower. Currently LED light sources tend to range from a CRI of 80 up to the middle 90s with improvements expected over time. For general domestic use a CRI of 80 is OK but if you have anything special to illuminate or want really accurate colour rendering you should be looking at products in the 90s.