A full line of sapphire and ruby balls for a wide range of applications requiring precise tolerances and superior mechanical and optical properties are available from Meller Optics, Inc. of Providence, Rhode Island. Meller Sapphire & Ruby Balls come in 42 inch/metric sizes from 0.1 mm to 0.5” dia. with 0.000025” sphericity and ±0.0001” basic diameter tolerance. Featuring Mohs 9 hardness which is second only to diamond, they have surface finishes to 80-20 scratch-dig, are impervious to most chemicals, solvents, and detergents and have a 2,000°C melting point. Now available A/R coated, Meller Sapphire & Ruby Balls can be precision ground into plano-convex lenses and provide 85 to 98% typical transmission, depending upon configuration. They are suitable for use in fine instruments and medical devices as ball and roller bearings, spacers, check valves, piston valve seats, stylus tips, and fiberoptic or endoscopic lens systems. Meller Sapphire & Ruby Balls are priced according to material, size, and quantity; delivered from stock. Samples and price quotations are available upon request.