Although graphene gives diamond a solid run for its money when it comes to being the most useful assembly of carbon atoms, both have the distinct property of material scientists still trying to figure out all their properties and potential applications. This includes something like the melting curve of diamond and potential phases beyond this diamond lattice phase that occur when exposed to extreme pressures and temperatures. Such as those experienced on a planetary scale and during inertial confinement fusion (ICF).
In this research (paywalled) by researchers at the Lawrence Livermore National Laboratory (LLNL), it was investigated how close theoretical simulations were to physical reality by blasting diamond samples with a laser. This ablated the surface and sent a shockwave through the material that caused it to melt. Using X-ray diffraction data this entire process was followed, elucidating the exact melting temperature under such conditions.
This revealed that previous estimates based on earlier experiments had been off by many hundreds of degrees, giving a far better idea of how diamond responds to such extreme pressures and temperatures. Where such information is very relevant is in fields like planetary science where diamonds can occur naturally and being able to predict their presence can be essential.
The other application, and the primary reason why LLNL does this kind of research is for the sake of ICF at the national ignition facility (NIF), which is the best way to investigate the behavior of e.g. hydrogen isotopes under extreme conditions like those of nuclear weapons.
Unfortunately this research will have no impact on practical power generation using nuclear fusion, as the only viable path there involves forms of magnetic confinement fusion (MCF), but it’s still pretty rad to improve our understanding this carbon form.