Some thoughts I haven't seen mentioned in the comments: 1. Diamonds, like gold, are highly portable pieces of wealth that hold value across economic shifts. Wh

Some thoughts I haven't seen mentioned in the comments: 1. Diamonds, like gold, are highly portable pieces of wealth that hold value across economic shifts. When rich people go on the run, they usually carry hidden diamonds with them. 2. A good looking woman in certain jobs will be approached very frequently by other men. It's not just waitresses, think pharma rep. The ring is an effective shield, and the bigger the better. Putting these thoughts together, the pointless rock is actually providing a good amount of security to the woman. Even if you disappeared, or if she wanted to disappear, the diamond will always have value and can get her through a few months expenses. Second, you're helping her avoid confrontation in public life. Now realistically, some women have a back office job where everyone already knows their marital status. Many women today don't need the precious stone as pawnable thing of last resort. So I don't think its wrong for a couple to skeptically evaluate the value prop I've described above.