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.
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.)
Diamond hones are made from very small, industrial grade, diamonds adhered to the face of a metal or plastic plate. Also, because Diamonds are so much harder than any of the other sharpening materials, they tend to cut very fast and last much longer than the other whetstone materials. But, they are also often more expensive to purchase. In addition, Diamond Stones generally consist of three different styles consisting of a solid metal plate coated with an adhesive and diamond dust with holes in the plate to allow the swarf to escape, a solid plate without holes for sharpening tools with corners that might catch in the holes, and a plastic plate with islands of exposed plastic interspersed with the adhesive and diamond dust to act as a lubricant.
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.
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.
Your stroke can be straight or circular, from "hilt to tip" OR "tip to hilt," whichever is more comfortable. If you're using a small portable sharpener, stroke the blade in nearly a straight direction. Remember to always cut into the stone and never pull or drag your edge backwards. The blade edge should face in the same direction as your stroke. So, you're essentially moving the metal away from the edge. We recommend the circular stroke as it helps you maintain your angle instead of having to find it every time you lift the knife from the stone.
This wedge ends up short of a "point" to a much larger degree than the picture would indicate. The metal stops short, but then there is black non-slide "tape" applied to one side, and white "slide" tape applied to the other side, which makes the wedge even thicker than it appears in the photo, which means that in practice the end of wedge is even more truncated. So I have a hard time supporting my knives accurately on this wedge while sliding them down into contact with my stones. Prior to buying this wedge I just used a wooden wedge I cut off of a 3" by 3" post using a miter saw, said wedgewhich has a much less truncated end. That wooden wedge unfortunately absorbs water from my Japanese Waterstones. But I will try spraying polyurethane on that wooden wedge to help waterproof itand try again. If that doesn't work I will try to find a 3" by 3" plastic trim board somewhere and cut a wedge off the end of that. Note that you can buy 20 degree plastic wedges, but this is the first one I have found that does 15 degrees (nominal.) Note that Amazon also has the Blue AngleGuide set of wedges, but they are very small https://www.amazon.com/Angle-Guides-Sharpening-Knife-Stone/dp/B01N4QMO7U/ref=sr_1_4?ie=UTF8&qid=1499301705&sr=8-4&keywords=sharpening+angle+guide
Diamond sharpening stone delivers fast cutting and sharp edges. They are tougher in material and doesn’t flatten. Therefore, it is the best way on investment if you want such of the sharpener that easy to maintain and practical to use. Diamond sharpening stone doesn’t require water other than a spill. It is also applicable to use with lubrication if you wish to.
Mine came plain white then started to darken after a few weeks. About 4 weeks in it settled to a more natural stone/slate grey. The leather has darkened a bit too and remains soft and comfortable. The leather remains easy to adjust and my selected sizings stays in place firmly. Overall It feels, looks and works great. The knot and darker stone/leather compliment each other well.
However, because the Belgian Blue stone generally occurs in relatively wide columns with much thinner layers of Vielsalm Coticule on either side adjacent to the slate, the Belgian Blue stone is more plentiful that Coticule and thus, it’s somewhat less expensive. But, it’s also somewhat softer than Coticule and is not divided into different grades as Coticule is. Furthermore, because it is a softer stone than Coticule, it is sold without a substrate layer.