When using these diamond impregnated steel stones be sure to add water to the surface of the stone. Doing this will ensure long-life of the diamond surfaces, giving years of sharpening life. Afterall, a sharp knife is a safe knife.
To develop an edge on a homemade knife, hatchet or axe start with the coarse (Yellow) stone and gradually move to finer (Red) and finer yet (Blue) stones. Finally, finish your edge with a leather strop to hone your knife to razor sharp. Usually, factory-made knives will only require the fine (Blue) stone for a touch up of the edge and a terrific cutting experience.