The Suehiro Rika #5000 is the go to polishing stone in the shop, and what we use in our own sharpening progression for our sharpening service. #5000 is enough to build a near mirror polish and put the final touches on a screaming sharp edge.
We like this stone because it wears slowly, yet still works fast and has a great tactile feel to it unlike some other higher grit stones that can feel a little too smooth. And its not so terribly hard that it takes ages to flatten or work up a slurry. With only a few minutes of work, with light pressure and a nice slurry not only will this stone give you a shaving sharp edge, but it will leave your knife with a beautiful polish as well.