Wettability tests were performed for Cu, Ag, Au liquid drops on diamond substrates as well as measurements of mechanical contact strength (MCS) between solidified metal drops and diamond. The work of adhesion was calculated using data for metal surface tension and observed contact angles. Cu, Ag, Au (metals of the group I(B) of the Periodic Table) show non-monotonic changes of wettability and work of adhesion within their group in the sequence Au -> Cu -> Ag. The work of adhesion was found to be almost two times higher for Ag than for Cu and almost five times higher for Ag than for Au. Measured mechanical contact strength (MCS) was similar to 4 times higher, on average, for Ag/diamond samples than for Cu/diamond or Au/diamond samples. Maximum value of the MCS reached similar to 70 MPa for Ag/diamond samples. Non-monotonic changes of the wettability and work of adhesion observed for the group IB metals (Cu, Ag, Au) are discussed on the basis of classical London equation for the energy of van der Waals (vdW) bond for two atoms. (C) Koninklijke Brill NV, Leiden, 2009