Yeah, I think
Diamond is a bit tacky. I also think of a baseball/softball field, because our JV softball coach made us T-shirts that said "Diamonds are a girl's best friend" in the middle of a softball diamond. Pretty clever, huh? :D
Anyway, some other gem names I love (aside from
Ruby, which you already mentioned):
Amethyst - in one of my top combos
Emerald - also in one of my top combos
SapphireMoonstone - probably wouldn't use this though
Opal