Covalent bonds in diamond

[PatrickP2]

We all know that when we scratch a diamond with another diamond, millions and millions of covalent bonds are broken. I would like to ask what happens when a diamond burns in the atmosphere at temperatures above 750 C? Does the reaction of oxygen and carbon also break the bonds, or are we dealing with a different phenomenon here?

 

[DaveE]

How could it burn if the C-C bonds weren't broken?
I think these verbs in your question are essentially synonymous: burn (oxidize); reaction; break bonds.
Anyway, you could try asking google too. It knows more about chemistry than I do.
https://www.wtamu.edu/~cbaird/sq/2014/03/27/can-you-light-diamond-on-fire/