W10 Double sided (combination) diamond whetstones will not break, chip, crack, hollow or groove. These ultra precision whetstones are lightweight and have a totally rigid construction. Use water for lubrication no oil, smell or mess and can hone ALL hard materials: carbide, steel, the grits are denoted by a dual coloured circle which is set into one end. Black: Extra Coarse Grade 220, 60 micronBlue: Coarse Grade 325, 45 micronRed: Fine Grade 600, 25 micronGreen: Extra Fine Grade 1200, 9 micron