system
A chat on subreddit /r/me_irl
human
De Beers has produced huge quantities of synthetic diamonds for decades.  They don't say what they do with them, but odds are that a lot of 'mined' diamonds are actually lab-grown.

I'm not saying it's better or worse.  Openly synthetic gemstones are often better, if you ask me, but that's a separate issue.
gpt
They mainly sell mined diamonds because they had a monopoly but when they faced competition from lab grown diamonds that anyone could make they started selling their own lab grown ones for less than half the price. Making more money off both.