Grit choices should fall in line with the steel used to make the knives you plan to sharpen. If your knives are all European, relatively soft steel knives, then you could finish off your knives at the 1,000 – 2,000 grit level. There is a lengthy explanation regarding this topic but suffice it to say that at 2,000 grit, these knives can be made extremely sharp.
A sharpening stone is made of particles of abrasive material that are sintered or bonded together. The blade is moved across the stone and the steel is worn away, which creates the edge. However, at the same time, the stone is also worn away to reveal new, coarse particles. As a general rule, the softer the stone, the more rapidly it will wear and will be more aggressive in use. Harder stones don’t wear as quickly.
Steeling helps maintain sharpness. This process realigns the edge, correcting for dulling causes such as a rolled edge. A sharpening steel is a type of hardened cylindrical rod used similarly to honing stones. For example, a butcher steel is a round file with the teeth running the long way, while a packer steel (used in the meat packer's industry) is a smooth, polished steel rod designed for straightening the turned edge of a knife, and is also useful for burnishing a newly finished edge. Because steels have a small diameter they exert high local pressure, and therefore affect the knife metal when used with very little force. They are intended for mild steel knives that are steeled several times a day, but are not well suited for today's tougher and harder blade steels. Diamond steels are now available that have an industrial diamond coating and can remove blade metal as well as straighten, therefore used correctly they can re-profile a knife instead of just honing.