I generally use 2 diamond stones (on a steel core, as opposed to the plastic core). I don’t remember what grit number they are, but they are classified fine and extra fine. Those stones, with some honing oil and a leather strop impregnated with polishing compound is all I seem to need to provide razor sharp tools.
That being said, there is much to be said for achieving a mirror finish. And it all has to do with stress. Not the stress you get from your boss but the stress that’s defined as force divided by area. When a tool is sharpened, there are always valleys and peaks. When the tool is used, force is placed upon those peaks, resulting in a certain stress. These peaks will bend when the tool is used and then recover when the load is removed. When the stress reaches the ultimate tensile strength of the steel, it stays deformed, and results in a dull tool. The cure is to reduce both the number of peaks as well as the height of those peaks…..anything to reduce the stress.
Sharpening through the grits and then polishing does this (thus the mirror finish), and the tool stays sharp longer. The trick is to balance the time it takes to sharpen with the frequency of sharpening. For me, this has meant that I put away my waterstones and my Tormek for everything except the initial establishment of the edge and use the diamond stones and leather strop. It takes me less that 2 minutes to resharpen a chisel or plane iron and that includes the time it takes to pull the stones down and to put them back.