No woman I've asked likes the way brown diamonds look- even if you call them "chocolate".
The weird thing is, I can't imagine why anyone would like a plain diamond. It just looks like glass. Rubies, emeralds and sapphires are colorful and can compliment ones eyes, or clothes or accessories, while diamonds just don't attract attention. Unless there's a dozen of them, in which case you're bankrupt.
Of course, I'm just a man and I wouldn't understand anything a woman wants.