I think this is a trick question. I don't know what the best H2 "color" is, but, clearly, the best finish on an H2 is no color at all:
http://en.wikipedia.org/wiki/Black
It is "merely the absence of the wavelengths of the visible light spectrum."
http://www.physicsclassroom.com/Class/light/U12L2a.html
Nice trick question CO, but I'm not falling for it.