I have to agree that it's not a great sign if she insists on this. What other trendy stuff is she going to demand just because "everyone else does it"?

I'm somewhat recently divorced now, but one good thing about my ex is that she was never superficial like this. She was perfectly happy to get a $70 Titanium wedding band, and loved how lightweight it was, and never wanted a silly gemstone on her hand. We did get her a couple other rings with gemstones (much cheaper ones, and prettier too; I think one was Tanzanite?), for wearing at special occasions, but wearing a gemstone ring every day is impractical and dumb really; it's just going to get in your way, and worse it's easy to take it off and then lose it. I knew a guy once whose wife dropped her $10k diamond ring down the drain while doing dishes! (No, they didn't recover it.)