Question

boilingpoint of diamonds

Answer 1

"liquid diamond" could be achieved at about 10 GPa and 5000 K, which is equal to almost 99 thousand atmospheres and 4726.85 °C. 

Answer 2

Diamond (carbon) does not melt at 1 atm. It sublimes to vapor. Using carbon's theoretical phase diagram below (from Wikimedia), "liquid diamond" could be achieved at about 10 GPa and 5000 K, which is equal to almost 99 thousand atmospheres and 4726.85 °C. Originally