The performances of metal-bond of diamond cutting tools were investigated by changing the cobalt and bronze ratio conversely as the matrix material. Diamond tools were fabricated by cold pressing and sintering under pressure at the temperature up to 750 °C. Investigation of the microhardness behavior of the segments was showed that increasing the cobalt ratio causes the increase of the hardness of the matrix material. This caused to decrease of the wear rate of the matrix. Because the matrix wears more slowly than the diamonds, the space between the cutting edges and the matrix is constantly reduced. The swarf cannot be carried away properly, and the segment will continuously lose its ability to cut with higher cobalt contents.