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.
High Grit Stones: These are also known as finishing stones with the number range going up to 8000, and give you a super refined edge.  They work great with Western knives as they cutting edge resembles a “U” as opposed to a “V”. If you are using your knife to cut meat, then you can happily stop at 4000 or 6000 grit. If you are only using it for vegetables or fruit go all the way to the 8000.
I've been using this stone for months and have started to find that, while the fine side does provide a nice sharp edge, the 400gr side is wearing my knives unevenly, which causes me to be unable to finely sharpen the entire length of the blade when moving to the fine side. The logo that is put in the middle of the 400gr side of the knife is causing more material to be removed than the rest of the blade when I'm sweeping across. I even verified this by going straight down the length of the fine side and watching the wear pattern come from the material coming off of the knife onto the stone.
A diamond plate is a steel plate, sometimes mounted on a plastic or resin base, coated with diamond grit, an abrasive that will grind metal. When they are mounted they are sometimes known as diamond stones.[12] The plate may have a series of holes cut in it that capture the swarf cast off as grinding takes place, and cuts costs by reducing the amount of abrasive surface area on each plate. Diamond plates can serve many purposes including sharpening steel tools, and for maintaining the flatness of man-made waterstones, which can become grooved or hollowed in use. Truing (flattening a stone whose shape has been changed as it wears away) is widely considered essential to the sharpening process but some hand sharpening techniques utilise the high points of a non-true stone. As the only part of a diamond plate to wear away is a very thin coating of grit and adhesive, and in a good diamond plate this wear is minimal due to diamond's hardness, a diamond plate retains its flatness. Rubbing the diamond plate on a whetstone to true (flatten) the whetstone is a modern alternative to more traditional truing methods.[13]
Japanese water stones – both natural and synthetic – are known for their superior sharpening performance, not only for Japanese tools, but also on their Western equivalents. The loosely bonded abrasive grit is washed out very quickly, as it blunts during the sharpening process; this exposes new, sharp, particles that can get to work on the blade. Water stones are lubricated only with water! Never use oil!
Therefore, the first step to choosing a whetstone is to determine your intended purpose and then choose your whetstone accordingly. For instance, when sharpening tools that do not require a fine edge, you should choose a relatively soft, coarse, stone such as a Norton Crystolon water stone. However, for sharpening tools that do require a fine edge, a somewhat harder Norton India oil stone would be a good choice. But, for sharpening hunting knives where an exceptionally fine edge is required, a Novaculite or Coticule oil stone would be the best but, most expensive, choice. So, the process of choosing the correct whetstone for any given purpose is to first determine how fast you would like for the stone to cut and how fine an edge you need, and then choose either a soft, coarse, stone or, a hard, fine, stone of the appropriate type and grit.
This is a great sharpener for budget conscious cooks. You can use it with equal facility whether you’re right or left handed, it has a convenient finger guard to cut down on accidents and most important, it only takes a few swipes on a regular basis to keep your knives in tip-top condition. It’s not glamorous. It won’t add anything substantive to your kitchen decor. But it will ensure your knives are always ready for whatever dish you have in mind.
I recommend it as a lightweight alternative to larger stone for smaller knives. Leather necklace is comfortable and seems strong. I conditioned it for suppleness and swim with it on tightened as a choker. Stone is small, dog-tag size. I use it with water. Functional for small folder knives and multi-tools. Not useful for large fixed blades, since you can't make a long stroke. Small to grip. I use double-sided tape on one side to keep it in place on a flat rock. Not sure of grit, seems like around 1000. It took a while, but i got my old boy scout knife sharp.
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. 

I've always wanted to sharpen knives on water stones, and this set gave me the motivation to finally give it a shot. The price is amazing for the quality and content of the set. It comes with all the grits you need to sharpen anything... I usually start on the 400 grit if the knife is very dull, or directly on the 1000 grit if it's not too dull. The 3000 and 8000 grit stones are softer and ideal after the coarser stones. The online learning section is truly amazing, much better than I expected. A convenient place with instructional videos and many articles about knife sharpening. Only downside is that the knives are now so sharp I need to be very careful using them... but that's a good thing! I feel like I fell in love with knife sharpening again.
Method 3: Use a Sharpening Stone. This is the best method by far. Not only will it give you the best edge, it also removes the least amount of material. With a fine enough grit, your knife should be able to take hairs off your arm when you've finished. Additionally—and I'm not kidding about the importance of this one—the act of sharpening your knife will help you create a much stronger bond with your blade, and a knife that is treated respectfully will behave much better for its owner. The only problem? It takes a little know-how.
Clamp-style sharpening tools use a clamp with several holes with predefined angles. The stone is mounted on a rod and is pulled through these holes, so that the angle remains consistent. Another system is the crock stick setup, where two sticks are put into a plastic or wooden base to form a V shape. When the knife is pulled up the V, the angle is held so long as the blade is held perpendicular to the base. Several cutlery manufacturers now offer electric knife sharpeners with multiple stages with at least one grinding stage. These electric sharpeners are typically used in the kitchen but have the ability to sharpen blades such as pocket or tactical knives. The main benefit of using an electric sharpener is speed with many models that can complete the sharpening process in one to two minutes. The disadvantage is that the sharpening angle is fixed so some specialized knives, like a Japanese style Santoku, may need additional attention to sharpen to the ideal angle.
Again, burr formation is critical to success and if you are using a 1,000 grit stone on a dull knife, you may be there for a while but it will form. If you are grinding on one side for more than 3-4 minutes, flip the knife and work the opposite side, always feeling for a burr with your thumb on the opposite side to which you are working on. Remember, the fatigued metal is being forced down the blade towards the edge of the edge by your actions and the abrasive properties of the stone.
Begin with your lower-grit stone. Place the heel of your knife on the far edge of the stone, holding the blade gently but firmly with both hands at a 15- to 20-degree angle. Using even pressure, slowly drag the knife over the stone toward you down the length of the stone while simultaneously moving the knife such that the contact point moves toward the tip of the blade.
An important but often confusing area of sharpening is knowing when you're done with one stone and ready for the next finer grit. On coarse stones it is very easy. When you sharpen one side you will notice a burr forming on the opposite side of the edge. This burr is hard to see but is easy to feel. Very carefully feel for the burr by gently running your hand from the spine to the edge. (Do not run your finger along the knife edge from heel to tip, that's only asking for trouble!) A burr is formed when your stone removes material directly at the edge. The burr will move from one side of your knife to another as you alternate sharpening sides. Make sure you have felt the burr jump between both sides before you move on to the next finer stone. That will ensure that you have sharpened both sides effectively. The finer grits are done the same way but the burr is much smaller. On the finest grits you may not be able to notice the burr at all. Testing the knife sharpness will tell you when you're done. (Learn how you can test to see if your knife is sharp.) 
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