An investigation was undertaken to elucidate the mechanisms for the fracture failure of brazed diamonds in wire sawing. Diamonds were brazed by high-frequency induction in vacuum. The changes of compressive strength and the appearances of the diamonds at different brazing temperatures were obtained. The morphologies of the diamonds after sawing were also observed. Together with the stress analysis of a brazed grit, it is found that the fracture failure of brazed grit is the result of the brittle fracture happening on the root section of the grit, the interface between the grit and the brazing alloy. The degradation of mechanical properties of grits in brazing is a key factor to the reduction of their resistance to fracture. Lower machining forces as well as grit exposure are in favor of preventing grits from fracture.