Also note that the metal swarf seen on the stone isn't equal to the metal amount that is removed. For example, if you hone for about one minute on a DMT 325, and one minute on a Shapton Pro 12k, than you will get what I mean. The shapton will be full of swarf, where the DMT will look almost clean, and the DMT is worlds faster than the 12k pro. A lot of very small metal filings look blacker than fewer bigger filings.