KitchenIQ's Diamond Sharpening Stones feature multiple layers of micron-sized monocrystalline diamonds bonded in nickel to a flat metal surface. The unique sharpening surface has an overlapping oval hold design that speeds sharpening by collecting and holding the metal filings which ordinarily build up during the sharpening process. These stones are excellent for hand sharpening of double-beveled straight edge kitchen knives and single-beveled Japanese/Asian edge blades of all sizes.