Answer: The boiling point refers to the constant temperature at which a substance boils and changes its form from a liquid into a gaseous state whereas the melting point of a substance can be defined as the constant temperature at which the state of the substance changes from solid to liquid at atmospheric pressure.
In case of Diamond, the melting point is 3550 degrees Celsius and the boiling point is 4830 degrees Celsius which are quite high. It is due to the molecular structure of diamond as a great amount of energy in the form of heat is required to break the strong covalent bond that exists between its carbon atoms.