A lot has been written about sharpening stones and their classifications depending on quality, mostly based on the grit count. As with everything, the more deeply you go into a subject, the more complicated it gets—even though at the beginning, it looks quite simple and straightforward.
For those who would like to know more details about sharpening stones, I recommend this article. For those of you who want a shortcut to the basic differences among sharpening stones, it is fairly simple and requires the sense of sight and touch.
There are two ways to quickly verify qualities of a particular sharpening stone: close visual observation of the grit, and the “touch,” that is, how it feels when you rub your fingers across the stone. Together, they will tell us if it is coarse, medium or fine.
The coarse ones are rough, their composition is based on larger particles that will eat the bevel of the scythe blade more quickly, and, as a result, we will have to peen the blade more frequently since the previously peened bevel will be worn away sooner. These stones also will wear out fast, especially on those areas of initial contact with the blade. While the stone is pulling an edge from the blade, the blade also does its own damage to the stone—wearing the large particles away, despite their hardness.
The medium coarse, usually 300–500 grit, is in my opinion the one-size-fits-all stone, and usually by applying more or less pressure against the blade, the medium stones can substitute either the coarse or the fine ones.
The fine ones are also very easy to recognize. We almost don’t see the single particles that form them, so smooth is their surface. Upon examination, they feel almost like a polished ceramic surface. This fine ones last far longer since they are very compact and hard.
Ideally we should pass these stones along the blade in order, coarse, medium then fine. But no one does it. The coarse does the harder job of removing material from the bevel, the medium smoothes it off and this fine one will give it a nice clean finish to the bevel—resulting in a quick, easy and clean cut.
Some stones are extracted from a quarry and shaped. These are natural stones. The others are manipulated into their final form. Personally I like the natural ones, even if their look can give the impression that they are poorly made or even unfinished. If you live in the country, chances are that you might pass through a place where you can get natural sharpening stones by the side of the road. If not of the best quality, they will at least be good enough to sharpen most of your tools.
If you take a closer look at the bunny photo, above, you will see coarse, medium and fine stones. Can you see the difference?
Stay sharp, my friends.