Through the ages, the lapidary of Cambay, India, has invented many indigenous materials for gem cutting and polishing. One such material is the polishing powder derived as a by-product of perforating ornamental silica beads by using a diamond-tipped bow drill. Over 95% of the beads manufactured in this area are derived from chalcedony varieties mined in nearby Ratanpura-Jhagadia in the Bharuch district. Silica powder derived from drilling of the beads is refined by wet sieving and heating to make it suitable for polishing hard stones like ruby, sapphire, and emerald. The author, at the Department of Geology, University of Baroda, Vadodara, studied the grain size of two samples using a SACPZ Schimadzu Particle Size Analyser and found the particles to be 1 micron or less in diameter. The use of the diamond-tipped bow drill is continued because of the excellent quality polishing material derived as a by-product.