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English, the Naniwa Germany site is for wholesale.
Maybe its not the only source or they do offer more variety on request, since fine-tools has them.
Guess I'm going to pay that guy a visit. He's...

English just click on the little german flag on the left side menu of www.fine-tools.com
then choose Schärfwerkzeuge. It gets you a list similar to the english one.
Then there is a link to the...

English they do!
http://www.feinewerkzeuge.de/superstone3000-8000a.jpg
Super-Kombischleifstein Naniwa
Körnung: 3000/8000
http://www.feinewerkzeuge.de/superstone800-5000a.jpg
...

The problem is that you cannot measure the finer grits at all, since a mesh sieve is only so big.
The industry more or less gives a clue (whenever they have a clue).
Their grit size might be an...