There was a discovery in 2024 on how to make diamonds under atmospheric pressure. https://en.wikipedia.org/wiki/Synthetic_diamond#Crystallization_inside_liquid

There was a discovery in 2024 on how to make diamonds under atmospheric pressure. https://en.wikipedia.org/wiki/Synthetic_diamond#Crystallization_inside_liquid_metal https://en.wikipedia.org/wiki/Synthetic_diamond#Crystallizat... I thing that method can only produce small crystals, although I think the authors said something along the lines that it would probably be possible to further evolve the method to make them bigger.