DMT A4XX Whetstone Knife Sharpener and Diamond Sharpening Stone for Use with Aligner, 4 Inches, Extra Extra Coarse

These are just the right grit for putting a fine edge back on a slightly dulled knife. Don't recommend them for resharpening. You will need the blue ones for that, or even the black to start a new edge. These are fine for putting back a razor edge on a used blade that is already well sharpened.

Very good stone.

This is a fine diamond whetstone used for putting the finishing touches on a sharp blade. This particular stone is for smaller blades. If you're dealing with larger tools (axes, hatchets, etc.), you'll want a larger version of this. Excellent stuff, and I'll only get these from DMT.

The aligner kit that this stone works with is handy and most people should be able to put a decent edge on a knife with not much practice or know-how. This stone makes an edge good enough for average kitchen work. You do need the extra-extra fine stone to get an edge that comes close to being nicely sharp. Apparently it is expected that a diamond stone leaves a slightly rough edge. It cuts so fast and leaves tiny grooves in the beveled edge.Update 11-5-10I may have found a significant flaw in using diamond stones to sharpen knives and tools. I am not an expert at this, and I have not seen this mentioned anywhere else, so take it with a grain of salt.The edge of the knives that I have been sharpening, while sharp, do not hold that sharp edge very long.First, no matter how well you sharpen an edge, it is not perfect. The edge has little microscopic teeth on it. Similar to a saw. These `teeth' on a knife are not uniform in size, shape, and spacing, as on a saw. Nor are they rigid as on a saw. On a knife, when you cut something, these weak little teeth bend this way or that way, and the knife begins to feel dull.My theory:Those little bits of diamond grit on a diamond stone are, as you know, very, very hard. They cut very fast. They also cut very deep. They make deeper little grooves, on the beveled edge, than any other type of sharpening stone. These deeper grooves make larger teeth on the edge of the knife. A larger tooth is inherently weaker, and will bend more easily. Also, without going into great detail, the deeper grooves cause each little tooth to have less physical support, making them weaker still. They will bend even more easily.No matter what you use to sharpen an edge, those little teeth are created. They are always present. It appears to me that a diamond grit stone causes weaker teeth that bend more easily. The result is that the edge does not stay sharp as long as when other sharpening materials are used.More comment:Because diamond stones sharpen so fast and so easily, I still like them, and will still use them. I may try to find some other sharpening stone to use as a final sharpening step, to put a more `finished' edge on a knife.

Value

Works well with my Ruyxin sharpener. Note that this stones need seasoning, as is clearly stated in the packaging. That means they will end up feeling less gritty after a couple uses.

Works quite well

I bought this coarse stone along with some of the other DMT stones awhile ago and have become a huge fan. This particular stone is very effective at repairing an edge, but what I'm most impressed with is the quality. The construction of the stone is solid and tolerances are excellent. This truly will be a lifetime tool for me - which is an important consideration when I buy tools. It's a great example of a quality product made in the USA.