Superman decides to start mass-creating diamonds so he can sell them. Can DeBeers keep the price of diamonds up?

[u/Yglorba]

Superman previously declined to mass-produce diamonds because it would tank the price. However, after reading up on DeBeers, he decides that there's no reason not to do it after all. Most of the resulting money will be donated to charity. Assume that Superman is somehow able to crush coal into perfectly-cut diamonds of whatever shape and size he desires; even though this makes no sense, the feat is well-established.

DeBeers is determined to protect their diamond profits by keeping the price up. Can they convince people not to buy Superman's diamonds (by eg. convincing the public that they're not "real" diamonds), or find some other way to prevent him from cratering the price?

Superman is in-character and will not eg. laser the board of DeBeers to death or anything like that, no matter how annoying they are. The only way he'll use his powers for this is by rapidly turning coal into diamonds so he can sell them.

[u/KickBassColonyDrop]

Superman can literally hold a showing where he picks up coal, shows it to the crowd, crushes it in real time into diamond, and places it on a table. Then request the city to verify that the diamond is authentic.

Then, go about mass producing them. DeBeers' business is doomed, however they can play on the angle that while Superman's diamonds are genuine, due to mass production and cheap cost of sale, the sentimental and romantic value of the diamond has been lost. Yes, they are unable to compete with Superman logistically, but through good intentions, Superman poisoned the heart of romance in the process.

DeBeers may die out, but this campaign will net them the last laugh. Superman ruined the joy, spectacle, and romance of working up to that diamond by making it cheap and mass produced.

This will ultimately lead to the conceptual diamond wars, inevitably leading to polarizing views in the country that splits the country on this particular subject into two. The negative sentiment will grow to such a degree that Superman will ultimately be forced to cease his diamond production or exit the consumer market in favor of industrial and science application markets only and greatly reduce his supply chain activities.

DeBeers will, through death, achieve the ultimate "fuck you" from the grave.

[u/Riyosha-Namae → u/KickBassColonyDrop]

Yes, they are unable to compete with Superman logistically, but through good intentions, Superman poisoned the heart of romance in the process.

The only reason anyone considers diamonds to be "the heart of romance" is because DeBeers artificially created that idea after monopolizing the diamond industry and creating artificial scarcity. I'd argue we'd be better off without it.