Abstract: The process and device (1) for positioning several single crystals (2) on a support (3) for their simultaneous cutting in directions well defined relative to the crystal structure of each single crystal; they avoid the adjustment in the machine and minimize the cutting time by providing a positioning outside the machine about angles of rotation (d,g) obtained mathematically from measured and/or given data and which position each geometric single crystal in a plane perpendicular to the cutting direction (z'") whilst bringing the cutting plane of each single crystal (2) parallel to the cutting direction of the machine. The device for practicing the process comprises a frame (5), a gripping device (8) mounted rotatably on the frame and carrying single crystals (2) and a rotatable plate (11) adapted to maintain the cutting support (3) belonging both to the positioning device (1) and to the cutting machine.