These state-of-the-art sharpening stones will remain flat forever and are backed by our 100% Lifetime Satisfaction Guarantee. Our 4″ Ceramic Stone Set is non-lubricating, putting an end to the need for oil, water and clean up. Fast, easy, durable. The dark stone (approximately 800 grit) is for shaping and the initial sharpening stage. The white stone (approximately 8000 grit) begins the final honing and polishing process. Once you try these ceramic stones, you will never use anything else.