Abstract: A process for cutting a diamond to realize an invisible mounting by using cuts situated below the girdle in which may be engaged the mounting. According to the invention the notches (7) have the shape of a dihedron (4) of which the two surfaces (5-6) are situated on both sides of the plane of the natural table along which is oriented the polished table (1), the two surfaces (5-6) of each dihedron being themselves polished by using a sawing machine in which the diamond carrier is movably mounted along a direction parallel to the plane of the disk and driven in an alternating motion along this direction, the surface of the disk being coated with a mixture of bort and gum arabic diluted with water, the polishing speed of the surface of the disk with respect to the diamond being comprised between 2500 and 3200 m/min., with about 10 passages per minute of the diamond in contact with the surface of the disk.