WONDERSTONE-Natural Sharpening Stone for your kitchen knives Natural stone, easy and efficient sharpening stone for your kitchen knives. Bring your knives back to life after the first use! No oil needed. We recommend to soak the stone in the water before use for the best performance. Gray stone with fine grit to protect your knives, easy to use when you need it. Give fast result and last a life time. 100% satisfaction! Very similar to Japanese natural sharpening stone but more affordable.