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The new cerax are a bit harder, and maybe a bit faster. If the cerax, new cerax and the "legendary" Gokumyo use the same scale, since they are all from Suehiro, 10k grit=1 micron for their scale....

From what I have seen, they are close to Shapton stones, and most japanese manufacturers use the same grit scale. There are some where 1 micron is 12 and some that 1 micron is 15, but those are small...