Understanding Colour Quality:
In a study of colour preference, the Lighting Research Center investigated whether sources, both warm and cool, with high levels of both CRI (above 80) and GAI (above 80 and less than 100) were judged better than ones with high levels of just CRI or just GAI.
It was found that a light source with both a high level of CRI and a high level of GAI will render the display more naturally than the other two sources of the same correlated colour temperature (CCT), but having either a high level of CRI or a high level of GAI.
GAI is the better indicator of subjective ratings of vividness and, based upon the results of a previous study, colour discrimination.
High levels of GAI can distort colours, reinforcing the need for both an upper and a lower limit for the GAI of a light source for optimal colour rendering. Similarly, high values of CRI do not ensure, by themselves, high ratings of naturalness