Grinding is generally done with some type of sharpening stone. Sharpening stones come in coarse and fine grits and can be described as hard or soft based on whether the grit comes free of the stone with use. Many sources of naturally occurring stones exist around the world; some types known to the ancient world are no longer used, due to exhaustion of former resources or the ready availability of superior alternatives. Arkansas, USA is one source for honing stones, which are traditionally used with water or honing oil. India is another traditional source for stones. Ceramic hones are also common, especially for fine grit size. Japanese water stones (both artificial and natural) come in very fine grits. Before use, they are soaked in water, then flushed with water occasionally to expose new stone material to the knife blade. The mixture of water and abraded stone and knife material is known as slurry, which can assist with the polishing of the knife edge and help sharpen the blade. Generally, these are more costly than oilstones. Coated hones, which have an abrasive, sometimes diamonds, on a base of plastic or metal, are also available.
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. 

With its premium series Select II, the whetstone manufacturer Sigma Power Corporation from Tokyo addresses users of high-alloy steels such as HSS. These stones, too, are obviously intended to engender a grinding experience similar to that of natural stones. The special production process is expensive, but the Sigma Select II probably has no equal when it comes to demolishing steel.
first time buying a sharping stone. i bought this because i wanted to sharpen kitchen knives. you have to practice to get good at it, use a knife you don't care about because you might mess it up. there is some conflicting instructions online on how to use, water or no water. read as much as you can about using stones and practice, practice , practice. look up videos on youtube and internet. i had fun using it, BUY IF YOU WANT TO LEARN here is some stuff i found, they all sound like professionals this is a video that says don't use water this is a youtube video that i watched that uses water. *informative
The paper test - Remove your knife from the sharpener. Grab a piece of notebook paper and hold it vertically in your hand so that one edge is facing straight up. Now take the knife and push it down against this edge. If the blade cuts through without hesitation it’s sharp. If the paper simply crumples beneath the blade instead of cutting the blade needs a bit more work.

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.