Cubic boron nitride (CBN) is an extremely hard synthetic, crystalline material. CBN is superior in terms of abrasion resistance and oxidation resistance when in contact with steel alloys. It is especially good for stainless steel knives and hardened stainless steel cutting tools. CBN is not harder than diamond but is thermally and chemically more stable than pure diamond. Another feature of the CBN sharpener is that it retains its shape no matter how much it is used. In addition, this coating is located on both sides of this profiled stone. Grit size 25 micron, e.g., "fine".

How to use your CBN sharpener: Use no oil or water. Start by laying the blade flat on the stone, raise the blade spine approx. the thickness of the blade, and start moving the knife in circular motions. After restoring the edge to its original shape, you can also use a ceramic stone to “de-burr” the edge in order to get a razor-sharp edge.

The ink trick: Colour the edge with a felt-tip pen. You can check your progress in sharpening the knife by observing where the colour is removed.

How to check the sharpness: To check the sharpness of your knife, pull the edge very lightly on your fingernail. If it cuts, the knife is certainly sharp enough for most tasks.