If you propose to someone, and they say yes and they're all excited etc etc... What would you want them to do if they didn't like the ring? Whether they thought it was not the right size or just ugly, would you want them to tell you or just pretend they were ok and be grateful they got a ring at all?
Follow up, what would you do if they DID tell you, would you return it and get another ring?
I think wedding rings are stupid but if your partner wants one, get them a ring they actually like. The entire diamond is forever is a scam by the debeers crime family. Diamonds are worthless. Get something that your partner wants to wear that fits them.