Abstract: A machining tool comprising at least one diamond-coated functional region having a substrate surface composed of a hard metal or a ceramic material arranged beneath the diamond layer. The substrate surface contains hard material particles on the basis of carbide and/or nitride and/or oxide, which are embedded in a cobalt-containing binding matrix. The diamond layer is directly arranged on the substrate surface without cobalt having been removed by chemical or physical methods in substantial amounts out of the binding matrix of the substrate surface. Such a tool is produced by pre-treating a hard metal substrate surface with a positively charged ion beam, followed by conventional CVD-diamond coating directly onto the ion beam-pre-treated cobalt-containing substrate surface. The ion-underlying atoms thereby largely remain in the substrate. The tools according to the invention have good diamond layer bonding to the substrate and a high wear resistance.