ULTRA-SHARP Diamond Sharpening Stones are the best value we've ever seen in a diamond sharpener. We've tested every diamond sharpening stone made and the Ultra Sharp performs as well or better than any of them. These extremely fast working diamond stones are available in 300, 600 and 1200 grit. They will quickly sharpen anything with a cutting edge including high carbon, stainless steel, and ceramic knives. ULTRA-SHARP Diamond Sharpeners are made of micronized monocrystalline diamonds which results in faster sharpening speeds and greater durability. The diamonds are electroplated onto the metal plates. The key aspects of Ultra Sharp stones are the quality of the diamonds, the carefully graded particle size, and the dense, even distribution of the diamonds on the stones. The combination of these features makes the stones reliable, durable and an exceptional value. You won't be disappointed! The Best Value We've Seen in a diamond sharpening stone! High quality fine and extra-fine diamond sharpening stones included. 600 and 1200 grit. Quickly sharpens all knives and tools (including ceramic knives) Large Size: 8" x 3". Precision flatness guaranteed. No Questions Asked 100% Guarantee