Thought I'd see if anyone else has seen this. My Norton has basically gone to its eternal reward (4k side is pretty much used up) but saw lots of useful service for when I had it. The strange thing is, the 8k side seemingly didn't like to be soaked. If used as splash & go it worked fine (standard 8k Norton finish, working very well when doing strokes to dry ala JaNorton). But if soaked (which the 4k needed) it would darken quite a bit, turning almost brown. The feedback then was... "interesting". Felt very grabby & stuttery & actually dulled a few edges on it from not paying attention. Did not feel anything like a typical Norton 8k. I ended up lapping the 8k side a lot to fix it & each time, soon got down to regular yellow 8k, but after soaking for 15 min, it was back.

This was not a Mexican Norton, but 4k Italy; 8k US. Got it last year from a legit vendor. The 4k side worked fine. (It was a combo stone, so the whole thing had to be soaked.)