Carbonis in the Solar System

Carbon is common in the solar syst many of the asteroids have a lot of carbon on them. So it is quite likely that at the core of these gaseous planets, gas giants, like jupiter, saturn, uranus, neptune, et cetera, you would have a massive amount of diamond. You may even have a fully diamond core, possibly, possibly. It's possible. Because of the enormous atmospheric pressure that squeezes carbon into its diamond alotrope.