`  =Diamond doesn't ``burn`` at 800°C= The reference can be found in ANY advanced ceramics handbook! The surface sublimation (diamond disintergrates around circa 700-800°C) of diamond is an extremely slow process at ~700°C and the reaction yields carbon dioxide in general (of course depending if the reaction takes place in ``normal`` air, at standard conditions of atmospheric pressure etc), without presence of a flame, hence not ``burning``. Complete sublimation occurs circa 1700°C`