| 摘要 |
Notches (7) are cut in the corners of the diamond, under it's girdle in which the mounting engages. Each notch is in the form of a dihedron with two surfaces (5,6) on either side of the plane of the natural face of the diamond, which forms it's upper face (1). - The surface of each dihedron is polished. One surface (5) is mainly parallel to the upper face and the other surface (6) is inclined at an angle of at least 30 deg. w.r.t. the first surface. The notches are sawn or cut with a laser. - (10pp Dwg.No 3/8) USAB- US4738240 A The process ivolves using cuts situated below the girdle in which may be engaged the mounting. 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 of each dihedron are themselves polished by using a sawing machine in which the diamond carrier is movably mounted along a direction parallel to the plane of the disc and driven in an alternating motion along this direction. - The surface of the disc is coated with a mixture of bort and gum arabic diluted with water. The polishing speed of the surface of the disc with respect to the diamond is between 2500 and 3200 m/min., with about 10 passages per minute of the diamond in contact with the surface of the disc.
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