I can write some more about diamond coated sharpening stones because I can see on the internet that there are some questions about them. There are differences between expensive high
quality stones and less expensive ones. I have used both expensive ones and low cost types. The diamond dust and particles are bonded to a surface and depending on materials and quality this surface will either get worn or smoother in time. I have used some
stones on much bigger tasks than just sharpening SAKs blades and I noticed that in time they get smoother. Sometimes it is not much difference between quality products compared to less expensive ones. It seems
that the dust particles will wear off easier on the low cost ones but not always. It seems that sometimes it seems that the particles are completely gone. When using a pocket microscope I can see that there is some left but they are finer and this may be because
the “diamond” dust that is a material that should get hardness close to diamonds got variations in quality. Some stones use diamond particles while some use something close or another material. Sometimes it is just the bonding materials that
Worn diamond stones can be used for polishing the edge. I do believe that low cost stones will wear off, get smoother and have variations in the dust particles
hardness and abrasive abilities. Then again everything depend on use and if you use low pressure and make sure to use them only on knives then they will last a long time.
What I can say is that high quality diamond stones last longer and they will keep the surface grit for a longer time. I would also like to say that all diamond stones will get a bit smoother anyhow from use. The difference in grit on a 600 grit quality stone
will become a bit finer but not very much while a 600 grit low cost one will get 600-900 grit. I can also say that depending on what knives you are sharpening you can on harder steel use a coarse diamond stone before using the fine stone. If you use a low
cost fine surface as an abrasive for sharpening removing much metal then they will get worn. It is important to know that it is a moderate to light pressure that is the key on all sharpening. On the stones you can see that they have the holes or areas that are not covered with the particles. These are to catch the metal, burr and substances from the sharpening process. Some do not use these and it got nothing to do with the quality
that these must be on such a stone. Some do not use them and also depending on the quality some of these cavities can cause a problem. This is also depending on pressure applied and it can microchip the delicate edges. The reason for this is usually always
that people forget to clean them. When the stone will get worn these cavities will be very close to the same level as the dust surface particles. Sometimes the dust particles are on a certain depth so you will have years of sharpening before worn out. Some
high quality stones last and last. It is important to clean and brush away substances on the diamond stones.
Further i can say again that low cost diamond stones can last a very long time. I know some want to have a superior edge on their knives that are close to perfect. I have noticed that low cost stones that get
worn usually becomes even under the area you use. Diamond stones got an advantage that they will not curve like natural stones does it time. If the diamond stone is very low quality then it is used different materials and these will get worn uneven causing
problems when you are sharpening. To get the superior fine edge then the surface you are using the knife on must be even. For normal sharpening it is no problem. Diamond stones normally use synthetic diamonds and this is a very good material. It is more than
enough for sharpening normal knives to use synthetic and other hard abrasives. The crystalline form of the particles may be different.