A method of depositing a stable diamond film on a metal substrate includes pretreating a surface of the substrate and depositing a diamond film on the substrate by way of a multi-stage chemical vapor deposition, in which each subsequent stage is performed at progressively higher temperature. The deposited diamond may be doped with boron. The substrate may be titanium, a titanium alloy, iron, an iron alloy, or any other valve metal. The diamond deposition may be a high temperature chemical vapor deposition. The first deposition stage may optionally create a carbide of diamond and substrate, and an optional mixture of diamond and amorphous carbon may be deposited to bond this carbide layer to a subsequently applied layer. The resulting product may be used as an electrode, as a tooth or blade in a cutting tool, or may have many other uses.