Naniwa brand Diamond compound abrasive stone for knife sharpening. #400 for fast wear and new bevels Dimensions: 210mm x 75mm x 16mm. With Nagura stone for cleaning and abrading stone Naniwa diamond whetstones are incredibly hard, flat sharpening stones with diamond abrasives able to cut even the hardest modern blades. They are versatile, low maintenance, and have the ability to produce a mirror finish in minimal time. Each stone comes with a nagura stone for re-dressing the surface. Easy to use, simply soak or spray with water before use. We stock a range of Naniwa products for knife sharpening. They have become the gold standard for excellent quality abrasive stones designed for professional chefs. If you love Japanese steel, choosing Naniwa stones is your best bet for sharper edges.