D, E and F color diamonds are considered colorless. Meaning that they have no yellow tint. They are the rarest and as such most valuable. Even though the difference in coloration between D & E (and even D-F) color diamonds is impossible to see (unless compared).
Since the colorless family of diamonds is of the highest quality (color wise), it doesn't matter if you are mounting it in white gold or platinum, what setting you are using or what diamond shape you chose - they would look perfect.