Diamond coatings present extremely high hardness, good wear resistance and chemical inertness. Because of these excellent technological properties, diamond films are of interest for a large variety of applications. This study is to determine the absolute hardness of the diamond films. A series of classical Vickers indentation at several loads were applied at the surface of the specimen. The determination of the hardness of a thin diamond films necessitates the use of models for separating the influence of the substrate into the measurement.