Originally Posted by Ngchen

Actually, unless something dramatic has changed in the world of LEDs these past two years, red LEDs are more efficient than white ones in terms of light produced per unit of energy. (However, in terms of lumens, white may have an edge b/c the human eye is less sensitive to red than to green (most sensitive), etc. etc. and lumens takes this into account). Much more research has gone into the white ones though, because white is much prefered as something to see by, rather than as a "be seen" or indicator type light. White LEDs basically work by taking a BLUE LED and coating it with various combinations of phosphors that produce warmer colors when excited by blue light. The combination of the warmer colors plus the blue produces white.