CERAMIC STONES Our ceramic stones will not cup & require no lubricants, perfect for sharpening whittling & chip-carving knives which require a perfectly flat cutting edge, plus carving gouges & chisels. The secret? 94% aluminum oxide, the 2nd hardest naturally occurring composition. White Ultra Fine stone puts the finest mirror finish & final polish on a sharpened edge. Includes a non-slip box & instructions. White Ultra Fine=2,000+ grit 1/2x2x8".