Grade5 ruby or sapphire ball for bearings

Ruby ball ,sapphire crystal is one of corundum gemstones. it is mainly characterized by wear resistance, high hardness, corrosionresistance and small friction coefficient. it is an ideamaterial for precision instrument, machinery and bearing; sapphire glass has good infrared transmission and chemical stability. it is also widely used in all aspects of infrared military equipment, such as far-infraredsight, night vision camera and so on.