Warning: Spoilers for Supergirl Woman of Tomorrow #3 ahead!
Considering their sun-induced super strength and abilities, it's often been debated whether or not Supergirl or Superman could actually make diamonds by crushing coal, but Kara just confirmed that she indeed can. In DC's Supergirl Woman of Tomorrow #3 Kara proves once and for all that if she wanted, she could use her strength to obtain riches even greater than that of Gotham's Dark Knight.
Previously in this current Supergirl run, Kara flew to a planet with a red sun so her powers would diminish and she could get drunk and celebrate her birthday. Unfortunately, her attempt at peacefully inebriating herself led her straight to Ruthye, a young local searching for revenge against her father's killer, Krem of the Yellow Hills. Supergirl originally turns down Ruthye's request to be her gun for hire, but after Krem gravely injures Krypto, Kara takes the job. Ruthye and Supergirl form an unlikely team as they search the cosmos for the criminal. Up until now, Kara's hasn't been able to resort to her powers thanks to the red sun radiation, but now that they've returned to a planet with a yellow sun, Kara is once again able to let the full extent of her powers shinein remarkable fashion.
In Supergirl Woman of Tomorrow #3, by Tom King, Bilquis Evely, Matheus Lopes, Kara and Ruthye find themselves on Coronn in the town of Maypole. On their quest to hunt down Krem. they notice something off about the town. Kara quickly becomes concerned by the evasiveness and aggression of the town's inhabitants. Soon she finds out her concern is justified as she and Ruthye are ambushed in their hotel room. After that, Supergirl becomes extremely weary of leaving the young girl on her own and decides to take her with her as she patrols the town and its borders. This means that Ruthye is going to have to take a ride on Supergirl's shoulders for the first time back as they take to the skies. Kara hadn't used this method of transport on the planet since they arrived for fear of scaring Ruthye, but now she had no choice. It's because of this that Kara feels the need to remind Ruthye she has nothing to be afraid of since "these hands can turn coal into diamonds, so they're not going to let go."
It's been an eternal question for comic fans whether or not Superman could use his strength and heat vision to form diamonds from coal. Now, this simple passing statement has answered that he and Supergirl can, easily. This means that if either of them wanted to, they could shirk their hero duties and just spend some time exponentially growing their wealth. Wayne Enterprises may be an extremely successful conglomerate, but they don't have anything on the ability to make diamonds out of sheer strength and will power. Luckily, Supergirl and Superman aren't that materialistic and don't need expensive gadgets to fight crime, so they'll probably keep using their powers to help others instead of helping themselves.
Although, this revelation does raise a question. If the Kryptonians can so easily create diamonds, what's stopping them from making a bunch and sharing the wealth with people who really need it? If they have sworn to protect the Earth and its inhabitants, what's stopping them from helping those less fortunate? Hopefully, it's an issue of the time needed to form diamonds from coal, rather than a lack of caring. Either way, it's good to finally have a definitive answer to this long-debated question. Maybe sometime in the future fans will get to see this ability in action, but until then they're just going to have to imagine what would happen if Supergirl went full Scrooge McDuck.