I do have to question the grit ratings of these stones. I didn't notice anything before using them, but after a day, the 2000 grit actually felt courser than the 1000 grit side of the other stone. Whether that could be a byproduct of other factors or an indication of the more obvious, being that the grit ratings aren't accurate, I don't know. But that seemed to be the main criticism of cheaper whetstones, that their grit ratings often aren't accurate. Or maybe it's less a problem with accuracy and more a difference that most synthetic stones might have in common when being compared to much pricier natural stones?
This coarse grit whetstone is great for prepping old and dull knives that need to be sharpened with a fine grit stone. One of my good knives edge looked like someone had tried to chop barbed wire. After ten minutes on each side of the stone, the edge was smooth and free of imperfections. After it hit the knife with the fine grit stone, I was cutting onions and apples like hot butter! I would soak this stone for 12-24 hours before using. It sucks water like a sponge. The surface needs to be damp when you sharpen.
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.
Whichever method you choose, be it a waterstone (also known as a whetstone), or a pull-through (either V-shaped or ceramic wheels) it's important to regularly hone your knife with a honing steel, which we'll also cover below. You'll be pleased to hear that you won't have to reach for the stones too regularly – once every two or three months should suffice. 

Siliciclastic stone is a clastic, noncarbonate, sedimentary stone that is almost exclusively silica-bearing and exists as either a form of quartz or, another silicate mineral. In addition, hardened clay is also a sedimentary stone but, it is formed from organic materials such as plant and animal matter and thus, it is much softer than Siliciclastic However, when silicon sediment is suspended in a clay matrix and then naturally hardened over thousands of years, it forms an excellent whetstone material; although, it is somewhat softer than Novaculite. Thus, because the geology of Japan once held large deposits of this type of stone it has been used for hundreds of years for sharpening tools, knives, and swords. However, unlike Novaculite, Belgian Blue, and Coticule, both natural and synthetic Japanese whetstones use water for lubrication and thus, they are commonly known as “Japanese Water Stones” because this type of stone is very porous. Thus, natural Japanese Water Stones must be soaked in water for up to twenty-four hours prior to use whereas, synthetic Japanese Water Stones can be soaked for only a few moments.
I purchased this set together with the 400/1000 grit stone assuming that some of my knives were quite dull and would need work on a coarse grit stone. Premium Whetstone Sharpening Stone 2 Side Grit 400/1000 | Knife Sharpener Waterstone with NonSlip Rubber Base & Flattening Stone. This is my first wetstone. First off I tried to sharpen my Chicago Cutlery boning knife. This knife is nearly thirty years old, has been abused in may ways and was quite dull. It was very difficult for me to get a burr on this blade, which I attribute to poor technique. Next I moved on to my Henckels Professional S paring and chef's knives. The paring knife was moderately sharp and was modestly improved after working over all three grits of stone. It would cut paper but again it was difficult to develop a burr with this blade. Undaunted I switched to the chef's knife. This knife is twenty years old and has never been professionally re-sharpened. I have sharpened it twice with a Lanksey sharpening system which marred the finish but did put a good edge on the blade. Lansky Standard Coarse Sharpening System with Fine Hones. The chef's knife was moderately dull and had several pits visible on the cutting surface. I modified my technique for passing the knife over the stone and worked the chef's knife over the 400 grit stone aggressively and eventually I was able to get a burr to form from the tip of the knife all the way to the handle. From there it was a simple process of reforming the burr on the 1000 grit stone and then finishing on the 6000. After sharpening, the chef's knife easily and cleanly slices a tomato with very light pressure and is in my opinion very sharp. Not sushi knife sharp but more than enough for the chopping and slicing I expect of it. I'm looking forward to going back and working both the boning knife and the paring knife over again. Don't expect a good result from this product the first time you use it. Watch videos on using a wetstone, expect to spend at least twenty minutes per knife at first, and practice forming a burr. If you can form a burr, you will be able to successfully sharpen your knife. 

The final Chef’s Choice sharpener on our list is the 316 Diamond Sharpener. Like the 15XV the 316 is at its best when used to sharpen Asian-style knives and it does so with unflinching effectiveness and speed. This is a compact, 2-stage electric sharpener that produces the 15 degree edge so favored in Asian cutlery. Ideal for the preparation of sashimi or sushi.
The paper test - Remove your knife from the sharpener. Grab a piece of notebook paper and hold it vertically in your hand so that one edge is facing straight up. Now take the knife and push it down against this edge. If the blade cuts through without hesitation it’s sharp. If the paper simply crumples beneath the blade instead of cutting the blade needs a bit more work.
Now you may wonder, if a finer stone produces a better cutting edge why do I need a coarse stone at all? The answer is that finer stones work much more slowly than coarse ones. The amount of metal a fine stone removes with each pass is much less than what a coarse stone removes. If you have an edge with a good shape to it from a coarse stone, this is not a problem because the fine stone doesn’t have to remove much metal to improve the edge. If the edge is dull, it will take many times longer to reshape it with a fine stone than it would with a coarse one.
I bought this and Unimi's 600/1000 whetstone at the same time. Curiously, reviews are currently blocked for their 600/1000 model, as amazon wouldn't let me leave one for it. Considering the conspicuous absence of reviews in the other stone's listing, one can only assume they're being censored for everyone. So, maybe I should be more critical of these stones, and use them a while longer before giving them any praise? But I've had a very positive experience with them so far, and the 600/1000 stone was the one I found most useful.
We’ve shown you how to keep knives sharp before, and even discussed why water stones are best, but this crash course is quick, fast, and gets to the point. In most cases the most the average person at home can do is either hone their blade with a honing steel, which straightens and lines up the blade’s edge, but it doesn’t sharpen it. Alternatively you could run it through a handheld or electronic sharpener, but depending on the model you use it can do more harm than good.
To summarize, Shapton Glass 500, 1,000 and 2,000 is a good combination and if you would like to throw in the 4,000 grit stone in lieu of the 2,000 that is good as well. If your knives are very hard, ZDP 189 for example, this is a fantastic choice. (They are also excellent for tools, chisels etc. and they are the premier choice for many Straight Razor honers).

Once sufficiently wet, it's time to position the stone on something solid, so it doesn't move about during sharpening. Many come with holders, but you can just place it on a slightly damp tea towel on the table. The stone should be roughly perpendicular to your body, though Warner told me it is sometimes easier to angle it ever so slightly to the right (if you're right handed). 

Using the strength of industrial high precision superior mono-crystalline diamonds, Diamond Machining Technology (DMT) have created a durable longer-lasting flat sharpening surface that will efficiently sharpen, hone, deburr and polish almost any type of knife or cutting tool. The DMT set contains 3 one-sided whetstones that have extra-fine, fine, and coarse grits which means you have a complete sharpening system at your fingertips.
The speed and polishing ability of waterstones attract many sharpeners. Waterstones sharpen quickly and are available in fine polishing grits not found in other stone types. The ability to flatten the stones is a necessity when sharpening with waterstones, so a starting set should include a flattening stone of some kind. Our article, How to Flatten a Waterstone, has more information about keeping waterstones flat.
Understanding Grit: You’ll see a bunch of numbers being thrown around when discussing the grit of a sharpening stone. The number refers to the size of the grit. The larger the number, the finer the grit. A good beginner stone would be a two-sided stone with #400 and #1000 grit. The #400 grit is the courser stone for working out the nicks and imperfections, the #1000 grit is for refining.
As you continue to repeat strokes on the first time, eventually a tiny burr will form on the other side of the blade. To check for it, place the blade on your thumb, and pull it backwards. If the burr has formed, it should catch slightly on your thumb (with really fine grit stones, say 2000 or above, you won't feel this). This may take up to 30 or 40 strokes, and is the indication that you should switch and start sharpening the other side.
The Juuma sharpening and honing stones offer a simplified working principle while at the same time ensuring the highest possible quality in the offered grits. Juuma Cobalt Blue stones are made of an aluminium oxide and a bonding agent. Adding cobalt serves to slow stone abrasion and increase the speed of sharpening. The speed bonus is especially marked when stoning blue steel (blue paper steel that is often used for Japanese planes and chisels). The cobalt gives the stones their blue colour. Juuma is our proprietary brand. Juuma sharpening stones are produced by a renowned Japanese whetstone manufacturer.
I like the fact that there are two different grits (can be seen as two colors). the black rubber feet stick to the kitchen granite top like glue. The 1000 does a pretty good job of getting a knife roughly there and the 4000 puts on a fine polish for razor a sharp edge. I would go the extra step of stropping the knife after the grinding operation for an extra sharp edge.
This is a good size stone and has the two different grits needed for knife sharpening. No instructions were included, but there are many websites with written and video instructions, so this is not an issue for most people. A fair amount of dust is generated during the sharpening process, so protect the work surface and wash the knife after sharpening is completed.