Naniwa Japanese Nagura Dressing Stone, 600-grit

If you haven't tried a nagura, GET ONE. This 600 naniwa has been awesome for maintaining all of my stones. Keeps them clean and fresh, ready to bite!

I don't believe I have enough words to describe how good this little, apparently insignificant, stone is.
I used this stone now for a while to dress all my sharpening water stones and I can say it is really perfect for the job that was intended. It is hard enough to not wear down to fast and has the proper amount of abrasives to bring your sharpening stone in perfect sharpening state. Besides cleaning the stone of the steel particles it conditions the surface of the water stone for the next sharpening session, perfectly, The slightly matte but very smooth finish left after using this dressing stone, reveals fresh sharpening particles that makes the next sharpening session fast and easily predictable.On the top of it, if you are mindful when sharpening, regarding the coverage of the stone so you preserve its flatness as much as possible, covering the entire surface of the stone, whether you sharpen freehand or using a guide, using this dressing stone to condition the water stone after each sharpening session, also aids in keeping the sharpening stone very flat, reducing the need to flatten the stone all the time, process that leads to a lot of loss of abrasive material. In my case this allows me to go without using a diamond plate to flatten the sharpening stones for at least 20 sharpening sessions and I do this only if I find that the stone is out of flatness using a good straight edge.
I use this stone on any grit water stone regardless of its hardness, it is extremely fast and efficient.
The slurry left after use would have to be washed off from the sharpening stone, for any stones higher than 800 - 1000 grit.