ELI5 Coal To Diamond - Can we really turn coal into diamonds through applying the right pressure conditions?

Superman did it in Superman 3. If coal turns to diamonds through pressure, could we dump a bunch of coal on the ocean floor to turn them into diamonds faster?   ... We explain like i'm five!   Thank you to the r/explainlikeimfive community, and specifically the following reddit users whose questions and responses formed the basis of this conversation: rnbwmstr, bizitmap, stuthulhu, nevm, iamplasma & sir_beard   To the ELI5 community that has supported us so far, thanks for all your feedback and comments. Join us on Facebook: https://www.facebook.com/eli5ThePodcast/  or send us an e-mail: [email protected] ... we love hearing from you!