A method of planarizing a diamond film which generally includes orifices in the surface is described. The method includes first polishing the diamond film surface to reduce the surface roughness. A filler material is applied to the surface of the film to fill the orifices in the film. The film is polished to remove excess filler material and expose the diamond film surface. Also disclosed are planarized diamond films diamond substrate having a polished surface of both diamond and filler material and a variation in thickness of less than 8 percent
