In addition, there are three broad grades of Japanese Water Stones consisting of the Ara-to (rough stone), the Naka-to (middle/medium stone) and, the Shiage-to (finishing stone). However, it should be noted that the various grades of natural Japanese Water Stones vary widely in both density and grit size from stone to stone and thus, they do not translate well to American or European abrasive standards. Furthermore, because they are significantly softer than Novaculite, Japanese Water Stones must be flattened more often and do not last as long as a either Novaculite or Coticule stones. But, because they form a slurry of fine particles when used, they also do a superior job of both cutting and polishing.
Vielsalm Coticule on the other hand generally occurs in much more narrow layers sandwiched between the slate layer and the Belgian Blue layer and thus, it is both less plentiful and more expensive than Belgian Blue stone. Also, Coticule is divided into different grades and sometimes displays blemishes on the surface due to its proximity to the slate layer. Furthermore, it is somewhat harder than Belgium Blue stone and, due to its brittleness, it is bonded to a substrate layer of hard slate prior to sale to prevent the stone from breaking during use.
I recommend keeping two stones in your kit. One with a medium grit (around 800 or so) to perform major sharpening jobs, and one with a fine grit (at least 2,000) to tune the edge to a razor-sharp finish. For real pros, a stone with an ultra-fine grit (8,000 and above) will leave a mirror-like finish on your blade, but most cooks won't notice the difference in terms of cutting ability.
The sharpener has come a long way in the past couple of thousand years and yet it hasn’t. That is, while there have been incredible advances in the development of mechanical knife sharpeners the classic and very ancient sharpening stone is still with us and very much in use as you read this. The best knife sharpener for you will be one that meets the needs of your cuisine and your temperament but which, first and foremost, reliably produces the sharp knives (look after your knife!) you need with the least hassle.
Medium Grit Stones: The number range here is from 1000 to 3000, with the latter being the basic, go-to sharpening stone. If your knives have lost their edge and need a good sharpen, then this is the grit you should start with. Don’t use it too often or the knife wears down rapidly. If you like to sharpen regularly, then the 2000 and 3000 grit are the ideal choice as they are less coarse, but please remember they are designed for sharpening and not maintaining the edge.
When starting out sharpening, it won’t be long before you hear about the “toothy” vs “polished” edge. It will suffice to know that a 1k stone is going to give you an edge that will perform beautifully as will a knife finished at 5k. There is a belief that a knife that has a highly polished finish, 5k and up will be so polished that it’s toothy goodness will be erased. This knife will not bite into the skin of a tomato for example because the edge is too polished, it will slide over the top. This is not always true, if the knife has been sharpened well, i.e. if Side A and Side B of the blade meet precisely at the Apex of the knife, that edge will slide into a tomato quite beautifully. I have seen many brand new Japanese knives with highly polished 8k edges that no tomato skin can stand up to.
I had wanted a pair of sharpening stones for a while, so was enthused to get this last week. I watched a bunch of YouTube videos on how to use them and a deburring strop I also bought and wow, my kitchen and pocket knives are now wicked sharp. Pro tip: if you post anything about it on social media, family and friends will almost surely volunteer their knives for more practice...