In the previous post we looked at the color temperature, or color of the light. That actually has little to do with color rendering, which is the color of the objects under the light. See the difference? Either a warm source like incandescent or a cool source like daylight can render the color of objects nearly perfectly (my socks were blue under both.) It has to do with how much of the pigment is reflected back to your eye by the light source.
The new Lighting Facts Label (at left) required on light bulbs (lamps) sold in the US lists the color of the light, but not its color accuracy. Another new label (below) uses both. As a consumer of today's complex lighting sources, you need to know both. The color accuracy scale goes to 100. In most cases, choose the highest number you can afford. Something in the 80s for fluorescent and close to 90 for LED. If you have the opportunity to try multiple sources to see how they look in your final application, that is even better. Check color accuracy to avoid disappointment and purple...no, blue...no, purple socks - or worse!
Disclaimer: The metrics are imperfect and much more complicated than presented here, but a basic awareness is becoming more and more important as consumers move away from the simplicity of the incandescent lamp.
CCT = Correlated Color Temperature and
CRI = Color Rendering Index
Thank you to Metro Lighting for the use of the apples and color boxes for the illustrations.