Japanese Natural Waterstone (400-800 ??)

[Slur]

I recently bought this Japanese natural waterstone from here.




I like it very much. It gives me a very nice sensation when honing a razor. Now I understand why many people prefer natural stones.

In the website they say that it is corresponding to synthetic 400-800 grit.
I am not an expert, I am actually a beginner but I have a Norton 220/1000 comb, a Norton 4000/8000 comb, and some others. My opinion is that this stone is more than 1000grit. Maybe 2000 or 3000grit, I am not sure.

Is there anyone else here that has this natural Japanese hone?
Could you tell me your opinion about the grits of this stone?

Thank you.