Why is a diamond good conductor of heat but not electricity?

Diamond has a large macro molecular structure. It consists of a large network of covalent bonds that are arranged in a regular fashion. In diamond, each carbon atom is attached to other four carbon atoms in a tetrahedron manner. Due to the wave nature of electrons, electron wave can travel much smoother in crystals without bouncing. Due to the strong network of covalent bonds,mechanism of heat conduction via molecular vibration is further enhanced making it a good conductor of heat. All the valence electrons are involved in covalent bonds. Without any free moving electron available, diamond is the poor conductor of electricity