Graphite is also a type of carbon structure. It is very weak and has a hardness of 1 to 2 on the Moh's hardness scale. This is due to the weak bonds in its structure. This is a model of the structure of graphite.
Diamonds are a mineral form of carbon but are very different from graphite.
Unlike graphite, diamond is very hard, with a hardness of 10 on the Moh's scale. This is due to its strong covalent bonds. Good quality diamonds are clear and strong. Diamonds are excellent conductors of heat energy which makes them cold to the touch. Diamonds occur in various forms, including the diamond proper, bort, ballas, and carbonado.