To answer the original question acording to the above link:
"For best results the LED color should be the same as the lens color. As an example: a red lens will filter out all but the red portion of the light so if the light is all red, none or very little light will be blocked by the lens. The light from a White LED contains very little light in the red portion of the visible spectrum so most of the light would be filtered out by a red lens."