Natural diamond crystal structure of the internal grain boundaries so that the tool edge can, in theory, atomic-level flatness and sharpness; cut thin, high precision, small cutting force when cutting. Natural diamond's hardness, wear resistance, abrasion resistance and chemical stability to ensure long life of the tool, to ensure the continued long-term normal cutting and reduce its high thermal conductivity due to tool wear of precision parts to be processed; The coefficient can also lower the cutting temperature and thermal deformation of the parts.