Realize though that if she is THAT picky about the ring and doesn't like it, I'd tread lightly. Love is so much more than a piece of stone and metal. I know people who went through something like this. Guy bought ring, girl thought it was too small or some other selfish thing, and they broke up.

I say any ring you can afford should be perfect enough for her.

Although I cannot talk since I got my wife a ring which cost me about 4 months pay