Comment by km3r

Many artificial dyes use CYMK dye colors to build up to the final color when they are mixed by our eyes. Natural dyes will often truly be that color or a unique combination of non-CYMK colors. The result of this is non pure white light will reflect off the surface of the dyed object in different ways. It's a similar reason many LED lights look different than natural sunlight, with the LED lights using a combination of RGB.