This theory, studied for more than 30 years, has been successfully reproduced in a laboratory by scientists. They have succeeded in reproducing the pressure that causes carbon to turn into a diamond in nature, in conditions similar to what happens on these two planets. According to this study, the carbon particles that fall in the atmosphere change to graphite when they undergo a pressure increase when entering a dense zone. Continuing its fall, a new rise in pressure and temperature leads to the formation of solid diamonds.
In the near future, spacecraft could be sent to these planets to extract diamonds from the layers of the atmosphere of these giants, but they are very far from the Earth.