The invention of blue LEDs and the subsequent rapid rate of development of new phosphor and down-converting technologies have enabled the phenomenal growth of all LEDs in general lighting applications. White LEDs initially employed the use of a blue LED combined with a single phosphor with broad yellow emission. However, the light quality provided by this relatively simple solution was less than satisfactory, particularly in the red part of the visible spectrum. But more recently, new phosphors and phosphor combinations (green-yellow plus red) have been developed to provide a higher quality of light. While these advancements afford a significant improvement over previous offerings, phosphor technologies have yet to deliver desirable white light with rich color rendering ability along with the energy efficiency typically attributed to LEDs.