Check the listing for details. 3pcs Diamond Sharpening Stone Set 250/600/1200 Grit. Condition: New. Listed at 19.12 USD. 1. Material: The material of the sharpening stones is diamond.The stones are made using diamond abrasives, which are known for their high hardness and durability. Diamond is a popular material for sharpening stones because it provides efficient sharpening and has a long lifespan. The use of diamond abrasive ensures effective and precise sharpening of blades and cutting tools.2. Instructions: The recommended angle is typically around 30 degrees, but this may vary depending on the specific blade and sharpening requirements. Using moderate pressure, move the knife or tool back and forth across the sharpening stone, maintaining a consistent angle. Continue sharpening with smooth, alternating sides regularly to maintain even sharpening.3. Features: Each set of the sharpening stones kit includes 3pcs whetstone.