The sky is blue because blue light is scattered in all directions by the tiny molecules of air in Earth's atmosphere. Blue is scattered more than other colors because it travels as shorter, smaller waves. This is why we see a blue sky most of the time.
Answer:
Diamond have C-C bonds, so we do not expect difference in electronegativity since only are C atoms. In diamond the bonds are covalent as is expected for bonds between atoms with small difference in electronegativity (<1.7).