There are worse names, but there are better ones too.
I'd also stay away from Sapphire.
Why did you pick it by the way? Was it just a nice sound, or does it have special connotations to it? If it's the idea of the colour then Amber is equivalent and much less... uh... stripper-like, to quote some other posters.
It's also easily contracted to "spaz" which probably isn't a name your kid wants hanging around their neck for their whole school career.