(a) Diamonds have a very high melting point, as a huge amount of heat energy is required to break the strong covalent bonds in one crystal of a diamond. The melting point of diamond is above 3500o C.
(b) Uses of diamonds:
(i) As diamonds have an extraordinary shine, they are used in making jewellery.
(ii) Diamonds, due to their hardness, are used in instruments like glass cutters, grinders. They are also used as abrasives for polishing.