The present study was undertaken to examine the effects of metal coatings at the surfaces of diamonds impregnated in metal bond matrices. Diamonds with or without coatings were incorporated into same bond matrix to form two metal-diamond composites in order to reveal the effects of coatings. Diamonds with same coatings were applied to three bond matrices to check the influences of matrix properties on the effects of coatings. The transverse rupture strength (TRS) of the composites was measured to ssess their mechanical behavior. Circular sawing was also conducted to reveal the contribution of coatings to diamond retention. SEM was used to analyze the fractured surfaces of the composites. For same bond matrix, the coatings at diamonds were found to increase the TRS of the composites. However, it is difficult to compare the effects of coatings in different bond systems.