Historically, there are three broad grades of Japanese sharpening stones: the ara-to, or "rough stone", the naka-to or "middle/medium stone" and the shiage-to or "finishing stone". There is a fourth type of stone, the nagura, which is not used directly. Rather, it is used to form a cutting slurry on the shiage-to, which is often too hard to create the necessary slurry. Converting these names to absolute grit size is difficult as the classes are broad and natural stones have no inherent "grit number". As an indication, ara-to is probably (using a non-Japanese system of grading grit size) 500–1000 grit. The naka-to is probably 3000–5000 grit and the shiage-to is likely 7000–10000 grit. Current synthetic grit values range from extremely coarse, such as 120 grit, through extremely fine, such as 30,000 grit (less than half a micrometer abrasive particle size).[citation needed]
I purchased this set as a gift to myself and my wife we both love to cook . It’s only been a couple of months we use them almost every day and the knives are excellent they are razor-sharp but I highly recommend you order the Whetstone for keeping them that way. I’ve used many different knives sets over my life and these seem to be by for the best quality.
The type of stone refers to the material it is made with. You can find many different types, including diamond, ceramic, natural stone, and synthetic. I would only suggest diamond if you’re planning to be sharpening only ceramic knives. Many of the stones you’ll find on Amazon or other retails are made of Corundum, which is a crystalline form of aluminium oxide. It’s a fine choice for a beginner sharpening stone.
For instance, American Novaculite (aka Washita and Arkansas Stones) is a form of metamorphic Chert that produces some of the best known and best loved natural whetstones in existence. Then, there is a form of Belgian Coticule which has been known for providing extra-keen edges since Roman times and, there is a Japanese Siliciclastic sedimentary stone (aka Japanese Water Stones) which consist of a fine silicate particles suspended in a clay matrix. Plus, there are also various types of man-made whetstones available such as Silicon Carbide (aka Crystalon) stones and Aluminum Oxide (aka India Stones) as well as a synthetic Corundum (aka Ruby) rod and Aluminum Oxide impregnated ceramic rods as well as several different types of diamond hones. 

But if you start mixing brands or systems, you can get in trouble. Here’s an example: Say you want to use a soft Arkansas oilstone as your coarse stone and an extra-fine India (aluminum oxide) stone to finish things up. Well good luck , both of these stones are the same grit (22 micron). Your edge won’t improve when you move to the extra-fine stone.
To use a whetstone you run the knife's blade back and forth across the stone's surface and due to the constant friction with the stone, which acts like a piece of sandpaper, the knife's edge becomes razor sharp and has a brilliant mirror shine. If you are a beginner at using a whetstone it can a take a while to master the sharpening process, so here is a video to help you with your sharpening stone skills.
It depends. Meat cutters prefer this tooth because it makes their jobs easier and they are very good with a blade and know how to keep it sharp by avoiding bones, the cutting board, the table, etc... But that’s all they care about: cutting meat—which is more of a sawing action than a push or chopping cut. If you chop veggies all day, that’s a push cut and you’ll want a different edge; if you slice fruit, different edge. You get the picture.
The Whetstone comes in a small paper box with instructions. I checked the surface of the stone for flatness and it's about as flat as you can get so a check there. The stone seemed to be overstating the grit but after trying it out and giving it a few runs, the shaved material will actually fill in the gaps and give a good grit on which to sharpen knives on. The rubber feet are nice to have but I place a small mat or board under the stone to keep all the shavings from spilling.
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Some of the videos I watched suggested soaking the stone for 12-15 minutes prior to use. One suggested using vegetable oil on the surface versus water/soaking (I used water and presoaking it for 15-minutes). So instead of a simple 'out-of-the-box-and-use' approach, it required a bit of research before sharpening a knife. Otherwise I would have given this product a 5-star rating.

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.
If you only have one, it would be 1000. Personally, I have one much rougher to rehab knives with chips only. I also have an 8000 stone for final polish and a strop to finish. If you only used a 1000, it would probably work 80% as well as one that was refined a bit more. Does that last bit really matter? Not much, but I find that I can cut onions without tears with a very sharp knife.
Lubricate the stone. Some stones specifically use oil or water, and if that's the case, ensure you're using the recommended lubricant. Most importantly, whichever lubricant you choose, do not change it after the first use. When using oils, only use those approved for sharpening stones. Food oils such as vegetable and olive oil should never be applied! Some options like diamond stones, and others, don't need any lubricant at all, so be sure to check the stone's instructions.
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.