The major problem with wear-resistant diamond coatings in applications is the poor adhesion. The application of a buffer material holds some promise and has shown some successes. In this study, a commercially available process of electroless nickel plating was applied to steel as an intermediate layer for diamond chemical vapour depositions, by reason of the buffering material being softer than diamond and the stress relaxing, with increasing nickel thickness. Both continuous diamond film on a nickel plate and discrete diamond particles embedded in a nickel matrix were formed in a microwave plasma-assisted chemical vapour deposition system. The results of tribotesting indicated that the continuous diamond film as top coating usually suffers from the microcracks, while the composite-like coating improves the wear resistance significantly, though at the expense of losing some surface hardness in comparison with that of the pure diamond coating.