Powder samples for diffraction studies of selected materials have been prepared in this laboratory during the past 15 years using a commercial, slow-speed, diamond saw. The materials powdered include a wide range of ferrous and transition metal alloys as well as geological substances. Before sectioning begins, fresh oil is poured into the oil tray of the saw and the diamond, rim-impregnated, copper blade thoroughly cleaned. A typical blade is 10 cm in diameter and 3 mm thick. Powder produced as the blade cuts through the sample collects in and settles to the bottom of the oil tray. The oil, which bathes the sample surface during cutting and surrounds the powder debris after discharge into the tray, serves to prevent oxidation of most materials.