I shaved off an 8k for a long time because I didn't know any different.
It's the hand that holds the steel, not the stone underneath.I must’ve been very lucky with natural stones.
I’ve never bought one which I couldn’t get a great shave from.
Each one took me a while to decode but I get great shaves from slates, coticule, jnat, Ark, even a couple of stones I found near on beaches and rivers.
I don’t have many stones, two slates, one coti, one jnat, one ark but all feel nice, all cut close, you chaps may have different standards/different faces than me but that’s just my experience.
I don’t know what grit rating they’d approximate.
I’ve used lapping films and a Naniwa 12k in the past, they always felt ‘stingier’, not sure if that equates to more or less sharp.