The US Department of Energy has added “Color Rendering Index and LEDs” to its “LED Measurement” series of technology data sheets. The downloadable two-page document notes that the International Commission on Illumination (CIE) does not recommend the use of its color rendering index (CRI) with white-light LEDs. The recommendation was based on studies that considered both phosphor-coated white-light LEDs and red-green-blue LED clusters. Sections cover how CRI is measured and how the spectrum is “tuned” for high CRI. Spectral power distribution charts are shown for a fluorescent lamp and for a red-green-blue LED. Recommendations for using CRI in evaluating white LEDs are included.