How to measure CRI 

Here's the short answer: measuring CRI is complicated - so complicated that as a home or business owner, you don't actually have to worry about it.Light bulb manufacturers and retailers will supply this information-just keep an eye out for it on the packaging. 

Here is the long answer.According to the rensselaer polytechnic  institute: 

CRI is calculated from the difference in the chromaticities of eight CIE standard color samples (CIE 1995) when illuminated by a light source and bya a refrence illuminant of the same correlated color temperature (CCT), the smaller the average difference in chromaticities ,the higher the CRI,A CRI of 100 represents the maximum value,Lower CRI valuse indicate that some colors may appear unnatural when illuminated by the lamp, incandescent lamps have a CRI above 95, cool white fluroescent lamps have a CRI of 62, however fluorescent lamps containging rare earth phosphors are available with CRI values of 80 and above. 

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