One of the combinations of stones that I was introduced to several years ago is a unique one, it is a 500, 2,000 and 16,000 grit combination. I was apprehensive when I first tried this, that was thousands of knives ago, it works, it is fantastic combination. It is unique because the traditional way of thinking is that we should be doubling the grit sizes as we sharpen, for example, a 500 grit stone should be followed by a 1,000 grit, then 2,000 grit. This line of thought is meant to be flexible, it is a general rule only, I have broken it countless times.
Basically, there are 3 types of whetstones, Arato (rough grits), Nakato (medium grits) and Shiageto (fine grits). We normally use Nakato for the sharpening, but you can start with Arato to correct rough or damaged edge, and then Nakato and finish with Shiageto to get a fine and keen edge. All the sharpening methods and processes are same. However, it is not recommended to sharpen the opposite flat side of the blade with Arato
Aluminum-Oxide oil stones are very popular man-made sharpening stones produced by an abrasives company called Norton and which are commonly called India Stones. Generally less expensive than Arkansas stones (aka Novaculite), these stones are graded coarse, medium, and fine and are designed for fast cutting. Yet, when the fine grit is used, they can also produce a relatively fine edge. Also, because India Oil Stones are both softer and coarser than Arkansas Stones, they are commonly used in conjunction with Novaculite to cut the initial edge bevels or, repair extremely dull or damaged edges before refining and polishing the bevel with an Arkansas Stone.
Historically, there are three broad grades of Japanese sharpening stones: the ara-to, or "rough stone", the naka-to or "middle/medium stone" and the shiage-to or "finishing stone". There is a fourth type of stone, the nagura, which is not used directly. Rather, it is used to form a cutting slurry on the shiage-to, which is often too hard to create the necessary slurry. Converting these names to absolute grit size is difficult as the classes are broad and natural stones have no inherent "grit number". As an indication, ara-to is probably (using a non-Japanese system of grading grit size) 500–1000 grit. The naka-to is probably 3000–5000 grit and the shiage-to is likely 7000–10000 grit. Current synthetic grit values range from extremely coarse, such as 120 grit, through extremely fine, such as 30,000 grit (less than half a micrometer abrasive particle size).
Select the grit of the stone. Sharpening stones are available with different grit sizes. For example, you can choose fine, medium and coarse stones. You should use a coarse stone followed by a fine grit if your knives are dull. If your knives have been sharpened recently or they aren't too dull, consider using a medium grit. Try to use a grit level ranging from 325 (for coarse) to 1200 (for extra fine).
A: That depends almost entirely on how often you use them. If you are a professional chef who uses his or her knives every day then you should hone them every time you use your knives. But honing has its limits and over time your edge is going to become dull no matter what. Therefore your knives will need to be sharpened at least several times a year. Some chefs, in fact, will use a whetstone on an almost daily basis in order to ensure their knives are always razor sharp. Most of us, however, are not professional chefs and may not even touch our kitchen knives for days at a time. In that case, it’s probably a good idea to hone the edge after every couple of uses and have your knives sharpened once a year.