Jewel assembly parts are made of inner and outer metal sleeves and jewel elements. The inner sleeve is often made of H59 or H62 brass, the outer sleeve is often made of copper, 303 stainless steel, LY12 duralumin, etc.. Jewel elements which are made of synthetic sapphire and ruby single crystal are mainly groove shape, flat top surface, flat straight hole, flat olive hole, single oil groove straight hole, single oil groove olive hole, double oil groove straight hole,double oil groove olive hole, hyperboloid Straight holes and hyperboloid olive holes.

Since the main use surface of the assembly parts is the inner hole of the jewel, and the jewel material has good wear resistance. Its dry friction coefficient with steel is 0.14. The friction resistance is small; the sensitivity is high during use; and the service life is long. Therefore, it is widely used in the movable parts of precision instruments and military instruments in China and abroad.