3000 &10000# Grit Knife Razor Sharpener Fine Stone Polishing Whetstone Oilstone A fine-grained whetstone lubricated with water, used for fine sharpening. The Ruby sharpening stone and Agate Stone,For Polishing,Sharpening. Can Make Mirror surface, mirror finish. The Ruby Sharpening stone is made from sintered crystals of synthetic ruby. Its extremely hard, maintain their shape well and are resistant to wear.