I enjoy these stones so much that the feedback is not a deterrent at all for me, I don’t even think about it. The results are always nothing but top notch, they deliver exactly what I want, some of the sharpest knives I have ever produced were sharpened on Shapton Glass stones. They may be thinner but they last a very long time, they are easy to maintain as well,

Both Belgian Blue and Vielsalm Coticule are ancient stone layers found in the Belgian Ardenne Mountains with characteristics similar to both Novaculite and Siliciclastic sedimentary stone in that it is a metamorphic stone consisting of both gray and yellow volcanic ash mixed with tiny Spessartite Garnet crystals suspended in a clay matrix. However, due to its geology, both types of stone occur only in vertical seams sandwiched between two thick layers of bluish-purple slate and thus, they must be meticulously extracted mostly by hand. However, this type of extraction process is both very time-consuming and very labor-intensive and, quarrymen can only extract the stone for a few months each year due to inclement weather conditions. Consequently, both Belgium Blue and Coticule whetstones tend to be somewhat expensive.

Ye olde tomato test - After you have sharpened using one of the above sharpeners grab a firm tomato and try to slice it. If the blade is properly sharpened it will slice through the skin with virtually no effort and without pushing the skin inward first. If the skin is able to fight back against the blade then your knives are not properly sharpened yet.
Cerax and Suehiro stones from Suehiro are a little harder, and as such do not wear down as quickly as the classic Japanese water stones. The 8000 grit stone will perhaps give you the best cutting edge with a mirror polish on chisels and similar blades. Suehiro also makes a small combination stone for those who do not sharpen tools all that often and are reluctant to spend extra for a Cerax stone.
A: When it comes to the best knife sharpeners used in a domestic setting the abrasives used to sharpen the blade should last for quite a few years. When they do eventually wear out many of the best manufacturers will refurbish them for you, typically for a nominal fee. Again, however, unless you are using the sharpener on a daily basis (and there is virtually no reason the average person would do this), the sharpener should last for many years before ever needing service.
This 600/1,000 grit is my second Unimi knife sharpener, the first is 2,000/6,000 grit and I love them both. Both stones together produce very sharp and well polished knives that reduce the cutting effort and save time in the kitchen. I particularly appreciate that the manufacture printed the grit number on the side of each stone - that helps use the different grits in the proper sequence from the coarser to the finer. The stone comes with a non-slip silicone/rubber base which is very handy. 

Very interesting. If you work flat, 45 degree is what I was taught. Love the wet stones, especially the oiled ones. The nice thing about the leather part, is the mirror finish on a razor sharp blade which is a must if doing fine wood working, carving etc. A rough blade simply does not have the fine detailed dexterity. I find that the oiled sandpaper can work great as well, but found that the refined clay bars (white refined fired clay rounds and flats etc) does a wonderful job of keeping those razor edges refined, smooth as possible and then one can high polish them for smooth cutting. Believe me, when working wood for a flute, one wants that refined edge.! Learning how to hone a blade on a flat surface teaches one to work outside without a table/wall handy too...:) But we all have to start somewhere!:) Anyway, great stuff and a great start for those who want more from their tools!:) Cheers!

After you have completed a few passes over the stone on both sides, you can move to the final stage. This time it is P1 pressure, just enough pressure for you to control the knife. Ensure your stone is wet and now repeat the motions but with very very light pressure. You really need to focus here and ensure you are reaching the edge of the edge and again, just a few sweeps on both sides of the knife.
There will be a drawer that extends into the mechanism under the abrasives. Any detritus from the sharpening process drops into this drawer. Exactly where the drawer is located will differ from sharpener to sharpener but it shouldn’t be hard to find. Remove the drawer flick any material into the wastebasket and then wipe out the drawer with a damp cloth or tissue. You may want to use work gloves and goggles to protect your hands and eyes from any loose metal shavings. Once the drawer is clean and dry replace it. The exact means by which the sharpening mechanism itself is cleaned will vary from manufacturer to manufacturer. Consult your owners guide for specific details. Make sure you don’t introduce any grease or other lubricants into the sharpener unless specifically directed to do so by the owner’s manual. Also, the outside of the sharpener should come perfectly clean with just a damp cloth. Avoid using commercial cleaners or abrasives of any kind.

Frequently, our recommendation for beginning sharpeners is to start with diamond stones as their strengths make them ideal to build a sharpening toolkit around. Diamond stones are low maintenance and durable, lasting many years with only occasional cleaning. They are among the fastest stones to use making them time efficient. Diamond grit will handle even very hard steels, and diamond stones can be used for flattening waterstones. All these things make diamond stones a practical foundation for your sharpening toolkit.

A sharpening stone is a stone that has got a coarse side and usually a finer side, and that is going to take and re-shape your edge and get it back down thin enough in order to sharpen it. You are basically taking something that is blunt and thinning it back down. You have to remove all of this extra metal and get it back down to where it is thin enough to cut. Very simply, all a knife is is a very thin piece of steel to split whatever you are cutting. If the knife is obviously thicker, it is like trying to cut something with a chisel; it is not going to happen.
Serrated blades have a grind on one side of the blade. Only sharpen the grind side of the blade. Hold the sharpener at the angle that matches the original edge angle. Hold the knife with the edge away from you and the serrated side of the edge facing up. Set the tapered diamond sharpener in a serration so that you fill the indentation. Draw the sharpener towards the edge.
J. Kenji López-Alt is the Chief Culinary Advisor of Serious Eats, and author of the James Beard Award-nominated column The Food Lab, where he unravels the science of home cooking. A restaurant-trained chef and former Editor at Cook's Illustrated magazine, his first book, The Food Lab: Better Home Cooking Through Science is a New York Times Best-Seller, the recipient of a James Beard Award, and was named Cookbook of the Year in 2015 by the International Association of Culinary Professionals.