I feel a bit stupid for not knowing the answer to this question, but what is the difference between a 600 grit diamond stone and a 600 grit natural stone? I use them both (diamond first, then Arkansas stone) when I don't have access to my bench setup, and I've noticed that the diamond hone FEELS (not to be confused with IS) much coarser than the stone. Shouldn't they feel about the same?
The reason the diamond feels much coarser then the natural stone is because of the type of abrasive, diamonds cut much faster and more agressively. If the diamond stone is new it will also smooth out more with use.
Wesley called it. The reason the diamond feels coarser is because it is. There's really no comparing based on the numbered 'grit' rating anyway, if talking about different abrasives, each of which are usually graded to different standards. Diamond will always cut more aggressively, because it's harder (much). In particular, because natural stones are 'natural', there's really no objective way to measure grit, because there's an awful lot of variation in grain size within a single stone. The numbers assigned to them are really only useful when comparing different grades of the same abrasive type (all diamond, or all silicon carbide, or all aluminum oxide, or all natural), and then even from one particular source (manufacturer, or in the case of natural stones, the company quarrying, cutting and/or finishing them).
If using a mix of different abrasives in your sharpening scheme, the only reliable way to know where each 'fits' in the grit sequence is to use them and see how each will affect the finished results.
Generally speaking (there are always exceptions), for a given particle size of abrasive embedded in a consistent backing/binder, the scale of aggressiveness will usually go like this (from most aggressive to least):
diamond > silicon carbide > aluminum oxide > natural. Other factors like particle shape, friability (tendency to break down to smaller sizes under use) and individual hardness will influence the aggressiveness of some abrasives one way or another. Synthetic aluminum oxide, in particular, can be manufactured to a wide range of performance criteria (harder/softer, different particle shapes, friable or not, etc.).
David
