Abstract: A process forms an amorphous carbon film over a solid, which film has physical and chemical properties similar to those of diamond. Its ancillary objects are the solid bodies so coated and the self-sustained film obtained in a subsequent stage of dissolution of said substrate. The process includes generating a highly accelerated beam of carbon-hydrogenated ions, which beam is made to impact with sufficiently high energy on the surface of the substrate. The beam is concentrated by electrostatic lenses and homogenized by a magnetic mass separator. The process forms on a solid substrate, a film with properties similar to those of diamond, such as high hardness, high chemical stability, transparency, high heat conductivity and high electric resistivity; obtainable at ambient temperature, and which is simpler than known procedures.