[Roark66]

>The rock is a rock, but its exaorbitant price serves as a threshold for potential mate selection.

Indeed, but don't we already have much more practical things that serve the same purpose? For example a nice house/apartment or a car. Things we own, even what kind of furniture we have. All this communicates ones ability to provide for a family better than a rock. Gold itself is much better (preferably in bars or coins, not jewellery).

The problem with diamonds isn't that they are only a token of value. The problem is that they are extremely overvalued during the first purchase in jewellery. If one could buy an engagement ring for $10k then 10 years later sell it and make profit with regards to inflation (like it was a gold coin/bar) I would have no problem with it.

[corethree]

Those don't work. The sacrifice must have zero utility.

It's unequivocally clear to a woman and to all other women who she shows the ring too that the ring was 100 percent a tribute to her and only to her and only for that purpose.

Like peacocking the peacocks feather has zero utility. It is purely a mating ritual. A car or a house is not as clear because it has shared utility.

[corethree]

The keyword is "romance" any romantic gesture tends to have zero utility.

Buying a car or a house for a woman is not romantic at all. in terms of "romance" women tend to be looking for a clear and unequivocal display of devotion.