This wouldn't even be dumb if it weren't for the fact that diamonds have practically no significant resale value.

At least if you buy something like a gold ring, you'll know that it will be worth at least the melt value of the gold later on.

Well, that's true for pretty much any luxury brands. Look at how many people pay for the fancy "designer" clothing items and accessories with branding plastered all over it (Gucci, MK, Boss, etc), where the quality isn't any better than the "pleb" versions, and they're often more expensive than custom tailored items that'll look way better.

Vanity purchases are absolutely a thing. I'm glad my wife was cool with a relatively inexpensive ring (<$1k) and doesn't care much for jewelry in general. But the rest of her family is another story, and they love all of that vain nonsense. So instead of wasting all of our money looking rich, we're able to afford things like a home and plan for retirement.

I got my wife's ring with a synthetic diamond. It is beautiful, decently sized, fairly high standard in terms of cut and clarity, colour and flurourescents. It was cheaper and it made her happier because she is an ethical purchaser.

The diamonds in the surround, for someone unknown reason, were natural and were sourced all over the world. They were dofficult to source and put a dampener of the ethical efforts.

People who want to spend money will, but there is 0 need.