Stones are avilable in a variety of size, textures, and materials. Sharpening stones are produced from such man-made and natural materials as carborundum, silicon carbide, aluminum oxide, ceramic, whetstone, industrial diamond, and naturally occurring sandstone or Arkansas stone - a hard stone quarried from the Ozark Mountains.
The relative coarseness or fineness of the stone's material is referred to as its grit. The stone's grit determines degrees of fineness for the edge. Large stones - some with several sides and a reservoir for lubricating oil - have the advantage of accommodating large and heavy blades. Smaller stones may be a bit difficult to use on longer knives but are much easier to transport.