Color in Light Sources & Comparing LEDs - Learning Objectives
LED = Light Emitting Diodes - now the standard for new construction in the state of California, mandated by Title 24 energy codes power limits. These most restrictive power allowances in the world are signs of what to expect next in the rest of the country. LED bulbs (or lamps as the lighting industry calls them, or Light Engines as the lighting designers call them) are inherently color biased. Since the Blue White chip was developed for the commercial market, manufactures have been struggling with achieving balanced white light. A combination of coatings, voltage, age, and manufacturing processes all affect an LED's spectral and lumen output, industry terms for color and brightness.
Good lighting design should always include analysis of color rendering, light intensity, beam spread, flicker, and glare.
GLARE = Visual Disability
Due to the extremely small light source of LEDs, glare can cause visual disability ranging from averting the eyes to more intense sensations and slow visual adaptation recovery. "There's well over a million-fold change in intensity between a starlit night and a bright sunny day at the beach. This is a challenge for the nervous system because neurons have a very limited response range: -80mV to +50 mV of graded potential in the non-spiking cells of the retina, or 0 to about 200 spikes per second for ganglion cells. The retina solves this problem by adapting to the ambient level of illumination. If the light level changes by a relatively small amount, then the visual system compensates for the change almost immediately. However, if the light level changes by a lot, then the eye takes a long time to re-adjust." 
The bewildering array of light bulb choices is confusing. Industry professionals refer to light bulbs and light sources as 'lamps'. Examples of how colors appear under different light sources are discussed on this page. As LED lamps continue to evolve, there are many decisions to be made about color rendering (ability of light source to show color of objects and surfaces) and light output (intensity of light emitted measured in lumens).
R9 Color Rendering Test Colors
Color Rendering Index (CRI) indicates the effect of the light source's color spectrum on the color appearance of objects. The higher the number, the truer the appearance of the light on objects. Incandescent lighting is 100 on the CRI.
Regulations in California (Title 24) require 90 CRI or higher in Residential applications. Commercial projects often use light sources with 80 CRI.
As LED light source technology advances, the CRI is improving; however, it is important to learn about the color rendering and limitations of a particular light source before specifying or purchasing, since most light sources cannot be returned, since the wholesaler or retailer cannot tell how many hours the lamp (light source) has been burned.
R9 and CCT are additional color rendering measurements to be considered.
TM-30 Color Type Key: A. Nature B. Skin C. Textiles D. Paints E. Plastics F. Printed Materials G. Color Systems
TM-30 Color Rendering Test Colors
Lighting Facts - Comparing the numbers
DOE - Department of Energy