Shapton RockStar Whetstone 10000 GritAccessories Information The GlassStone series of sharpening stones uses a revolutionary design to provide great usability within a thin package formed from a combination of glass layers. The conventional image is that sharpening stones are large and heavy, but GlassStones are not only thin and light, but also strong, as layers of tempered glass are stuck together. GlassStones therefore have strong resistance to cracking or sudden breakage caused by