The following are my personal favourites and they are all synthetic stones, I do have experience with natural what stones but lets keep it simple, lets stick to synthetic water stones. Believe me, some of the world sharpest knives are sharpened solely on synthetic stones. Here are my personal favourites, I use these water stones every day and the order is not necessarily in priority, they are all good.
Low Grit Stones: A sharpening stone with grit number less than a 1000 is generally used for knives and tools that are damaged. If your blade has any nicks or chips in the blade, the stones will take care of them in a jiffy! They usually have a coarse side for nicks and chips, with the other side for general sharpening. Even if the knife’s edge has become totally blunt, the stone will re-sharpen it perfectly.
You might not need to spend hundreds of pounds to get the best knife sharpener, but you do need to know what you're doing. Warner gave me a crash course in the technique. As a newbie to this method, it took a while to get used to (especially since Warner handed me a knife that had never previously been sharpened) but after half an hour's practice and a little encouragement, I got the hang of it. Here's what I learned...
Cutting angle – With a manual stick or sharpening stone you set the angle yourself so this does not factor into the equation when choosing that type of sharpener. When shopping for an electric sharpener however it does. You’ll want to decide if you want your knives to have the 15 degree “Asian” style angle so that you can make precise cuts or the Western standard 20 degrees or 22-degree sharpening angle. Most people will opt for the 20 or 22-degree angle simply because their cuisine doesn’t call for a lot of finesse from their knives and those knives are probably of a heavier Western variety anyway.
Using the strength of industrial high precision superior mono-crystalline diamonds, Diamond Machining Technology (DMT) have created a durable longer-lasting flat sharpening surface that will efficiently sharpen, hone, deburr and polish almost any type of knife or cutting tool. The DMT set contains 3 one-sided whetstones that have extra-fine, fine, and coarse grits which means you have a complete sharpening system at your fingertips.
Sharpening stone/whetstones. Just as there are dozens of different ways to sharpen a knife, there are dozens of different sharpening stones. There are Japanese water stones, stones with diamond encrusted surfaces, and stones with different grades of grit. Again, choosing a stone is a matter of function and preference. Play around with different kinds of stones to find the one that gives you the results you’re looking for.
Steeling helps maintain sharpness. This process realigns the edge, correcting for dulling causes such as a rolled edge. A sharpening steel is a type of hardened cylindrical rod used similarly to honing stones. For example, a butcher steel is a round file with the teeth running the long way, while a packer steel (used in the meat packer's industry) is a smooth, polished steel rod designed for straightening the turned edge of a knife, and is also useful for burnishing a newly finished edge. Because steels have a small diameter they exert high local pressure, and therefore affect the knife metal when used with very little force. They are intended for mild steel knives that are steeled several times a day, but are not well suited for today's tougher and harder blade steels. Diamond steels are now available that have an industrial diamond coating and can remove blade metal as well as straighten, therefore used correctly they can re-profile a knife instead of just honing.