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If its shave ready all you would be doing is maintaining on the 12k which is totally do able, another option for that is a simple pasted strop. Way cheaper.

Great option. I find the problem with these cheap Chinese water stones is that no one knows their true grit rating and even less want to find that out by trying. It's a sad state of affairs.

You can't really tell by feel, try searching for the manufacturer. I bet you could hone a razor using it and a naniwa 8 or 10 or 12k. You would have to find out by testing it.