donsbulbs.com
Don's bulbs
rare light bulbs and lamps
glossary of termsinformation
definition of: COLOR RENDERING INDEX

What is COLOR RENDERING INDEX?

Color Rendering Index is an industry standard reference to a bulb on how well it renders color of objects it is illuminating.

Codes range is from 0 to 100, the higher the number the more vivid and lively things look under that light.

The lower the CRI rating the more ghostly (faded, dead) objects appear.


Workshops, factories and parking lot night lights might be acceptable for low CRI bulbs, but retail shops, beauty salons and art museums must use bulbs with a high CRI rating.


If you want your items and people to look good, then high CRI is required.

High CRI bulbs generally cost more to buy and cost more to operate as they have low lumens output per watt consumed.

Low CRI bulbs put out low quality light, but are very cheap to operate as they have high lumens output per watt consumed.

There are three main factors in describing the color portion of light, one being the Color Rendering Index (CRI), the 2nd being Color Temperature (or kelvin), and, the third unit, light output intensity (lumens, or, CP) are all important factor in describing light.

The noon day sun is considered to be 100 CRI rating.

Incandescent bulbs are generally near a 100 CRI rating, but of course are very expensive per watt to operate, plus a large portion of their output is in the infrared (heat) range of the spectrum.

For pleasant lighting, I recommend a minimum of 85 CRI rating.

For high quality retail I recommend a minimum of 92 to 95 CRI as the better your goodies look, the better they will sell.

Jewelry stores should use nothing less than 99 CRI (at least at the point of sale counter).

references for this page: COLOR RENDERING INDEX, CRI

references to this page: COLOR TEMPERATURE, ENCODINGS PHILIPS OLD BULBS, FULL SPECTRUM, LUMENS PER WATT, RE-RATE