Section 13 Articles of stone, plaster,cement,asbestos, mica or similar materials; ceramic products; glass and glassware 68 Articles of stone, plaster, cement, asbestos, mica or similar materials 68 04 Millstones, grindstones... of natural stone..., for grinding, etc Commodity Code Description 68 04 10 Millstones and grindstones for milling, grinding or pulping 68 04 21 Millstones, etc, of agglomerated synthetic or natural diamond 68 04 22 Millstones, etc, of other agglomerated abrasives or of ceramics 68 04 23 Millstones, etc, of natural stone 68 04 30 Hand sharpening or polishing stones