This contribution deals with a few topics closely related to the superconductivity in the heavily boron-doped diamond which are, in our opinion, not properly treated in the current literature. Attention is paid especially to the classification of metallic and insulating state, selection of pairing mechanism, limits of weak coupling approximation and to the influence of granularity on the superconducting transition.
Keywords: boron-doped diamond; metal-insulator transition; superconductivity.