That’s really useful info, thanks Milan!I have been working, a lot, on the NSK yesterday.
Two more observations : they are quite soft, not soft like a cerax 400 of course !, but soft like a hard whetstone like a shapton glass. So it's not soft but they will dish and you cant work with them like 30 minutes without flattening them. The 400 being the softest (but it a S so, normal). I guess all is compromise but I wish they would be a tad harder to be honest. Maybe a matter of preference but the work is so much more precise on harder stones. So like all stones, work as much all the surface of it as possible.
Second, even I had taste the diamond stones before with Practical sharpening and a Naniwa diamond 400, I was using still a lot a 200 grit whetstone and Naniwa pro 400 & 600. Diamonds stones really burnish while the normal whetstones are giving a kasumi (contrast between iron and steel, and within the iron, they will make dark the flatter part and burnish the high spots). And actually that effect of the whetstones is sometimes interesting for checking the surface. Yesterday, I was working and made progression 200, 400, 800 nsk, I knew one spot on my blade was a little critical but when working with the 800 the blade was looking good, scratch pattern even, so critical but was looking even enough. But going to a 1000 naniwa pro, I could see that there was a big high spot and the stone was hitting strongely there, so really not even enough.
So just be careful about that. They cut and make contact so well on the blade that they "hide" high spot a little. Consider to use a whetstone like Naniwa 1k or 2k in your progression, to check how the bevel will react with a softer stone that will make contrast.
Early on I used to really be bothered by the “streakiness” of my 800 and 3000 Choseras. Then I realised how much it told me about the bevel. Interesting idea to use them as part of the diamond stone progression to keep that diagnosis