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.
Last, it should be noted that dual-sided Coticule/Belgian Blue whetstones are also sometimes available which have a layer of Belgian Blue stone on one side and a layer of Coticule on the other. Thus, these whetstones provide a softer, more coarse, grit on one side and a harder, finer, grit on the other. Plus, due to the inherent toughness of the Belgian Blue stone, these dual-sided stones do not require a substrate layer.
Method 1: Use an Electric Sharpener. Quality electric sharpeners are an option, but I strongly discourage their use. First off, they remove a tremendous amount of material from your edge. Sharpen your knife a dozen times, and you've lost a good half-centimeter of width, throwing it off balance, and rendering any blade with a bolster (i.e. most high-end forged blades) useless. Secondly, even the best models provide only an adequate edge. If you don't mind replacing your knives every few years and are happy with the edge they give you, they'll do the trick. But a much better choice is to...

Put the pointed, narrow end of the sharpener up against the open end of the gut hook. The narrow, pointed end of the sharpener should face in toward the thickness of the blade, away from the edge of the gut hook. Match the angle of the sharpener to the original edge angle. This will maintain the correct sharpening angle and prevent you from getting cut by the blade tip. Hold the same angle when sharpening each side of the gut hook.
It is better to understand the difference in sharpening stone materials before you are going to make any decision. Among the available options in the market today, Waterstone, oilstone and diamond stone are the most common type of sharpening stone. Each of stones comes with advantages and disadvantages. Waterstone and oilstone are available in natural and synthetic models. Synthetic are the most common and easy to find as man makes them. As the use of natural stones (e.g. original Arkansas or Japanese natural whetstones) is has diminished in popularity, they are beginning to rare in the market. Artificial stones have a more consistent particle size and controlled with a tight mechanism in providing high-quality sharpening stone.
A blade's sharpness may be tested by checking if it "bites"—begins to cut by being drawn across an object without pressure. Specialized sticks exist to check bite, though one can also use a soft ballpoint pen, such as the common white Bic Stic. A thumbnail may be used[3] at the risk of a cut, or the edge of a sheet of paper. For kitchen knives, various vegetables may be used to check bite, notably carrots, tomatoes, or cucumbers. In testing in this way, any nicks are felt as obstacles.
Whetstone sharpener or sharpening stone has been here and there for a long time even before we born in the form of natural stone whatever they look like. Until today, the natural stone likely to be the most preferred options to sharpening things because of their versatility. As the technology improves, there are immerging new models and we are now not only having an option to the natural stone, but there are also other types considered better and more practical to use. The arrays can be bewildering to the inexperienced sharpeners that so often times many of them end up with a crap or wrong decision on stone type for their utensils.
However, due to limited natural deposits and extensive quarrying over the centuries, true, high quality, Japanese water stones are now few and far between and are very expensive. Thus, various companies are now producing synthetic Japanese Water Stones which generally have a more consistent composition and grit size than natural stones as well as often begin somewhat harder and thus, lasting a bit longer; not to mention being cheaper to purchase.
The stone – With a sharpening stone, the process is essentially the same as with the stick sharpener. The only difference is that you don’t hold the stone, you place it into its own holder (If it comes with one. If it doesn’t you’ll need to improvise) on a flat surface. Push the knife down the stone several times while holding it at a shallow angle and then flip it and pull it toward you several times to get the other side of the blade.
Oil Stones differ from water stones in that they require the use of honing oil to float the swarf (metal particles). Also, these stones are commonly made from one of three different materials consisting of Novaculite, Aluminum Oxide (Corundum), or Silicon Carbide (Carborundum) and they all use oil to lubricate the stone and suspend the swarf in order to prevent the stone from becoming clogged. Also, while Novaculite and Coticule are the most traditional types of oil stones, there are also synthetic oil stones made by the Norton abrasives company called “India Oil Stones”.
Table mounted device – Typically the manual powered table mounted sharpener looks virtually identical to the electric powered sharpener with a slot for each stage. Where they differ is that each slot in the manual powered sharpener has only one groove and you pull the blade through this groove toward you to sharpen the blade. Once the blade is sufficiently sharp you place it in the honing groove to refine the edge and pull it toward you again several times. If there is a third, cleaning, stage you repeat the process for that stage as well.
Aesthetics – While it’s true that most people keep their sharpener, (even their expensive mechanical sharpeners) in the drawer until it’s time to use them you’ll still want to be aware of whether your sharpener fits into the overall aesthetic of your kitchen when you do take it out to use. While sharpener designs are fairly limited to be sure you typically have some control over the color and finish of the device as well as design factors like whether the device is boxy or rounded in appearance. With a stone sharpener or a stick however you pretty much get what you get.

Honing is kind of like dusting the furniture while sharpening is more like reupholstering the furniture. Honing is purely a maintenance activity that should be regularly practiced to make sure the blade is clean and sharp as can be every time you use it. It’s easily done using a honing rod, a leather strop or a sharpening stone; as most stones have a side for sharpening and a side for honing. Honing is akin to trimming your hair to remove the split ends. It’s not a full on haircut. What it does is realign the tiny sharp protrusions along the edge of the blade that can be bent over with use, so that they stand more or less straight.

You must put the knife blade's position at the perfect angle which is called "against the stone." What's important is the blade should be facing opposite from you. Where you've determined where the bevel angle is located, then this is what you will position against the stone. It's a good idea to know the differences between various angles for certain blade uses. There's a certain height of the blade that it should be from the stone. You'll be able to find various charts on height of the blade online. Normally, for a pocket knife or kitchen knife, it'll be 17° - 22° angle against the stone. The "Rule of thumb" is the smaller the angle, the sharper the knife. Most makers will have it in the instruction or on their official website.
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.