No one wants to buy a drill or a power saw, they "want" a hole or a cut board.
No one wants to buy a diamond, they want the receiving mate to think positively about them when they look at the diamond. And they want their friends to think positive thoughts about them when they see the diamond. "Oh,.. her husband must really love her and they must have a great marriage since he spent so much money on her for something that really does not actually benefit the family other than perceived thoughts of love"
Usually it's the rings with owners that are comfortable with just having a diamond, not of any particular size, that is able to endure the storms of marriage.
On the other hand, it's the ones that expect or demand a large rock that have issues before the ink dries on the pre nup.
NJY