My girl gave me a very similar talk over this. She was very adamant that I not get her a diamond ring because a moissanite ring looks just as pretty, and costs way less. Specifically saying being more cost-effective like that would be much more impressive than how much raw cash I could blow on a diamond.
Between that, and Pippa's bit here, I wonder if this is just a thing going around with women these days. Are diamonds less "in" with more women caring about practicality more than just the idea of a diamond?