I bought a few diamond stones. They are all DMT which was the big player at the time. I find the diamond stone good to “true” other stones. The diamond stones however are pretty bad for sharpening knives though. Even for aggressive and coarse knife sharpening, I rather use a coarse ceramic sharpening stone like Imanishi 220.
I don’t think you are missing much for missing the diamond stones for sharpening. I suppose if you are trying to sharpening a ceramic knife, then the diamond stones will come into play. Short of that… no need.
