Abstract: The force on diamond saw blade during cutting of granite was measured and the number of diamonds truly taking part in cutting of the stone in the contact zone was estimated. As the results, the mean force applied on an individual diamond particulate is much smaller than the compressive static strength of the particulate. The failure of diamond saw blade at a low load is attributed to the thermal stress induced in repetitive cutting. The service life and the cutting efficiency are related to the ratio of the polished diamonds to the micro fractured ones. Namely, the higher the ratio of the polished diamonds to the micro fractured ones, the longer the service life of the saw blade and the higher the cutting efficiency.