Historically, there are three broad grades of Japanese sharpening stones: the ara-to, or "rough stone", the naka-to or "middle/medium stone" and the shiage-to or "finishing stone". There is a fourth type of stone, the nagura, which is not used directly. Rather, it is used to form a cutting slurry on the shiage-to, which is often too hard to create the necessary slurry. Converting these names to absolute grit size is difficult as the classes are broad and natural stones have no inherent "grit number". As an indication, ara-to is probably (using a non-Japanese system of grading grit size) 500–1000 grit. The naka-to is probably 3000–5000 grit and the shiage-to is likely 7000–10000 grit. Current synthetic grit values range from extremely coarse, such as 120 grit, through extremely fine, such as 30,000 grit (less than half a micrometer abrasive particle size).
A: You can sharpen your knives by hand using a stone or you can use a manual powered 1-stage, 2-stage or 3-stage sharpener or you can use a multi-stage electric powered sharpener. The choice is yours. Many people prefer not just the affordability but the precise control they have with an oil or water stone. While others opt for the more predictable results they get from an electric powered sharpener. It’s really a matter of taste.
If you wish, further polish or even strop the edge to the desired sharpness. This makes the edge better suited for "push cutting" (cutting directly into materials, pushing straight down without sliding the blade across the object) but generally impairs slicing ability: without the "microscopic serrations" left by grinding with a stone, the blade tends to not bite into things like tomato skins.
The Sharpening and Specialty lines of waterstones from Naniwa are available in several packages of three to five stones. The Specialty line is the same as the Sharpening line, but half the thickness and therefore less expensive. Both the Sharpening and the Specialty stones are 8 1/4" long by 2 3/4" wide, amply sized for most knives and tools. These are a higher grade stone that do not require soaking before use. While you would need a flattening stone in addition, these kits are a good way to enter into premium grade waterstones.
Let’s start with Arkansas. If you have heard about Arkansas oilstone, it uses the Novaculite stone that mined in Arkansas. The most expensive of Arkansas stone is the Hard Translucent model that begins to rare in the market. If you want to shop for Arkansas, they are available in different grade starting from Soft Arkansas, Hard Arkansas, Hard Black Arkansas and Hard Translucent Arkansas. The finest grade of Arkansas can shape such of mirror polishing edges.