Cemented carbides are composites which possess an excellent compromise between hardness and toughness. For years, to improve one property without decreasing the other one, the concept of graduated structure was widely studied. In this work, we present a process to create one-step continuous gradients of several millimetres within WCCo cermet, by the imbibition method. This process was applied on commercial drilling bit. The effects of this thermal processing are analysed in term of microhardness, cobalt concentration and grains size. The results obtained on PDC drill cutter show gradients of 540HV in WC-Co bit and 350HV in bit covered by the polycrystalline diamond layer. Such gradients have never been reported before to our knowledge.