I think it sounds out of place on a human being. The connotation with diamonds, to me, is conspicuous consumption and that's an uncomfortable thing to name a child after.
Generally-speaking, I think words for gemstones are out of place on human beings.
Amber,
Pearl, and
Opal are fine, but dated, and exist outside of its association with gemstones.
Amethyst,
Sapphire,
Emerald,
Topaz...? Ick.
Andrew
put a smile on your face - make the world a better place (: