A thermochemical polishing technique (using low carbon steel at 700 degree(s)C to 900 degree(s)C) was employed to reduce the roughness on the surface of diamond films from 20,000-40,000 angstroms rms to 30-45 angstroms rms. These polycrystalline films were grown by filament assisted chemical vapor deposition (FACVD) onto (100) oriented silicon substrates. SEM micrographs reveal etch pits in the films, and these limit the final polish which can be achieved. This paper show that the hot iron technique polishes a (111) oriented film, which is the hardest direction for abrasive polishing. Preliminary studies indicate that for chemical polishing there is no large difference between the polishing rates of diamond as a function of orientation.