Diamond has a giant covalent lattice structure. Each carbon atom forms a strong covalent bond with 4 other carbon atoms (forms 4 covalent bonds). As a result this makes diamond a hard structure.Diamond has a high melting and boiling point. This is because it requires a large amount of energy to overcome the strong covalent bonds between the carbon atoms.Additionally, diamond is a poor conductor of electricity, as there are no free electrons to move across the structure and carry a charge.