Illustration by Tang Yau Hoong

A great review by ArchLighting of the history and purpose of the color rendering index (CRI) and the need for a better system for analyzing color from lamps:

“Originally developed more than 40 years ago to address fluorescent lamp technology, CRI has proved a durable, if somewhat limited, metric for evaluating color-rendering ability. The advent of solid-state lighting (SSL), however, has highlighted the shortcomings of CRI, and created demand for a new way to measure color rendering that not only addresses conventional sources, but accurately depicts SSL product performance… ”

For more in-depth information on this topic, see these articles by the Lighting Research Center (LRC):

 What is gamut area?

A two metric proposal to specify the color-rendering properties of light sources for retail lighting

Beyond CRI: power point presentation