It goes without saying asking a woman how much her ring costs is rude. I think that extends to asking about carat weight, etc., when attempting to ascertain the cost without asking....
But so much worse is this little gem: Oh my god he must REALLY love you (in obvious reference to size/perceived quality).
What the actual fuck is that supposed to mean?!?! Yes, all couples who choose plain bands (or no rings) must not be in love.
The idea that many in our society view a direct correlation between ring size and love is sad and sickening and just stuck in my craw today.
I'd rather be directly asked how much something costs so I can decline to answer than stand there grappling for what to say? No, he doesn't really love me that much? Yes, he loves me more than other people love their wives? See, there's just no good response. Blank stare?