#3 Grade Natural Finishing Water Stone (Awase To) - The Japan Woodworker Catalog

Has anyone ever used one of these. There was one thread here about them, but the consensus was that it was too expensive.

Would these work like a coticule? The post stated more of an Escher type stone.

I have been emailing back and forth and the emails seem to state that the stone will go from 6k to 12k. Is this possible? Do I need to use a slurry?