... have specialised in the manufacture of Jewel bearings Synthetic white corundum, ruby, sapphire, glass, microcrystalline glass, cubic zirconia, natural agate ... Performance area):Type of precious stone bearings: synthetic white corundum, synthetic sapphire and ruby bearings, crystallite glass, cube zirconia, nature agate ... com Jewel bearing strucrture and technical parameter: Sapphire/Ruby Jewel Bearing