I've known what CRI for quite a while. The one thing I've always wondered is how companies claim 90+ CRI through a broad range of color temps. I always thought you'd have to have a light close to daylight to get 100 CRI. My mind was going crazy trying to comprehend how it would be possible to have 100 CRI across the light temp range. Especially since "white" lights are yellowish at one end and blueish at the other end of the kelvin range. That seems to be partially true. Daylight will give you the broadest range of colors. It would be nice if light manufacturers based the CRI on true daylight.
Anyway, my search for some of my CRI questions took me to http://www.fullspectrumsolutions.com/cri_explained.htm. It seems like a very good CRI explanation to me.