My girlfriend has told me this as well, thankfully. "If you throw away that much money on something so silly, I'll be pretty ****ed."
Have to wonder about people spending so long researching diamonds, and what's supposedly makes a 'good' diamond. If you have to spend so long working it out, what are the chances your Mrs is going to know the difference?
I doubt mine /hers when the time comes will have a diamond in it. Mainly because it's almost impossible to trace the life of a diamond and to know for sure someone, or some environment, wasn't completely screwed over in order to get it to you. But also because a diamond has zero meaning to either of us, so why would I drop so much cash on one?