A diamond deposition process is introduced and discussed together with its applications to several substrates. Diamond films are deposited by a direct current plasma discharge, assisted by electron emission from a hot cathode consisting of one or more tungsten filaments. This method allows good quality diamond film growth at a rate of up to 10 m h^-1 over a relatively large area (8 cm²). This deposition method is evaluated on different substrates (diamond, silicon, steels and alumina). Several surface pre-treatments are employed for each substrate: silicon diffusion, silicon interlayers, diamond seeding, and surface scratching using diamond and SiC powder. The results are described and analyzed in detail in each case. Deposited diamonds are characterized by Raman spectroscopy, electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). Potential applications are described below.