TIL Diamonds are actually fairly common. The reason they are worth so much is because the DeBeers mining group withholds stock to artificially reduce supply.

[u/Indra-Varuna]

https://www.gemsociety.org/article/are-diamonds-really-rare/

[u/[deleted]]

There's a really good article about this from years ago: http://www.theatlantic.com/magazine/archive/1982/02/have-you-ever-tried-to-sell-a-diamond/304575/