A line of high-purity calcined alumina polishing abrasives is made for grinding, lapping, and producing a superior finish on optics. The manufacturer says the line is available at a lower cost than diamond abrasives. The alumina abrasive powders can produce surface finishes to 10-5 scratch-dig on calcium fluoride, ferrites, germanium, silicon, stainless steel, zinc selenide, and zinc sulfide. They feature seven particle sizes from 0.05 to 3.0 µm. Ready to mix with deionized water, the powders come in two grades: a 99.98% pure grade for aggressive grinding and lapping. The grade has large agglomerated particles that break down under pressure for final polishing. The other, which is 99.99% pure, has controlled particle sizes for fine grinding and uniform polishing.