The demand for diamond was entirely driven by their very successful marketing campaign: https://www.theatlantic.com/international/archive/2015/02/ho...

IIRC the whole 2 months salary "rule" was also invented by them.

Which was brilliant (no pun) as it keeps up with inflation.

"Diamonds are forever. Coincidentally that's also the term of our sub-prime loan to get one."

Keeps up with wages

Hype has always played a huge role in the marketing of diamonds. It's been a myth for decades that the price of a diamond was somehow correlated with its rareness. Diamonds were, and are not, rare. DeBeers, as a cartel, was able to control the market and release diamonds from their cache such that the demand always out-stripped the supply. Now that diamonds are being mined outside of South Africa and the manufacture of synthetic stones is a reality, their hold is slipping away.

My wife doesn't like colored stones, so emeralds and sapphires are right out. We are looking at Moissanite stones. Not synthetic, but significantly cheaper than diamonds.

Moissanite is also synthetic (typically grown via a chemical vapor deposition process). It's not carbon (like diamonds), but made of SiC, a material long used for abrasives and more recently for high-power electronics and LEDs. The 4H-SiC polymorph is actually extraordinarily rare in nature, even moreso than diamonds!

We chose moissanites as the primary stones in my wife's engagement rings and everyone talks about how pretty it is. It's a bit more "firey" or "sparkly" than a regular diamond (because of more birefringence), but I guarantee no one outside a very highly trained jeweler would know the difference (if that's important to you). It's worth it to spend the money on the higher quality ones though, since just like diamonds, the inexpensive ones will have yellowish or greenish tints. Even still, they're at least an order of magnitude cheaper than similar diamonds ($600 vs. $6,500 at my quick search for ~1 carat).

I proposed to my fiancee with a Moissanite stone. One is hardly able to tell the difference. It looks like I paid many thousands of dollars more than I did for it, and no one is ever the wiser.

Go for it.

White sapphires are a thing.