Knife sharpeners by Fallkniven:

DC whetstones are newly developed combination whetstone sharpeners, where one side (the bright one) is a fine diamond whetstone (25 u.), and the other (the dark one) is a fine ceramic whetstone. A leather case is included. The yellow surface consists of titanium aluminium nitride (TAN) which considerable prolongs the functional life of the whetstone. We recommend a combination of diamond and ceramic knife sharpeners, where the diamond whetstone restores the wedge form of the blade edge, and the ceramic whetstone smoothes the edge to obtain long-term sharpness. Most of the time the sharpness provided by the whetstone is more than enough. Use Fallkniven whetstone knife sharpeners on Fallkniven kitchen cutlery knives,  hunting knives and pocket knives.