Metals are pretty important with regards to folk tales and legends. Werewolves can only be killed with a bullet made of silver, elves cannot touch anything that is made of iron. (remember Dark Elf in ff4)

if it's capitalized, you can be very sure that it is the metal itself, and not the color. But consider; if it is the color, something has to be making it appear that way, and fantasy settings aren't very fond of paint.