The Juuma sharpening and honing stones offer a simplified working principle while at the same time ensuring the highest possible quality in the offered grits. Juuma Cobalt Blue stones are made of an aluminium oxide and a bonding agent. Adding cobalt serves to slow stone abrasion and increase the speed of sharpening. The speed bonus is especially marked when stoning blue steel (blue paper steel that is often used for Japanese planes and chisels). The cobalt gives the stones their blue colour. Juuma is our proprietary brand. Juuma sharpening stones are produced by a renowned Japanese whetstone manufacturer.
Why, then, do so many of us shy away from the task? To put it bluntly, it's because it's a rather daunting process for the beginner. Your image of knife sharpening may consist of a hyper-masculine chef slashing away violently at a steel rod (we're looking at you, Gordon). Conversely, you might have seen cooks meticulously and methodically stroking their blade up and down a Japanese waterstone with more intricate attention to detail than a Flemish landscape.
Last, it should be noted that dual-sided Coticule/Belgian Blue whetstones are also sometimes available which have a layer of Belgian Blue stone on one side and a layer of Coticule on the other. Thus, these whetstones provide a softer, more coarse, grit on one side and a harder, finer, grit on the other. Plus, due to the inherent toughness of the Belgian Blue stone, these dual-sided stones do not require a substrate layer.
My first set of sharpening stones so I have nothing to compare them to. For $50, though, great price to get into the world of sharpening. Stones are great and easy to use. Was able to put hair shaving edges on knives. Took a couple of knives to feel comfortable and better with the process and how to sharpen, but the stones you get work great. Here's the secret though. Get the green leather stoping block as well. As great as the stone are, I have found that stroping the knife after the fact is what really brings out that razor edge. And after using the knife, stroping it again, will restore and keep it razor sharp. Hope you enjoy it as much as I am.