9 The more coarse the honing stone, the more material it will remove. The stone on the bottom is a #523 coarse stone that’s used for the rough cuts. The stone on top is an 818, which is a smooth stone used for finishing work. There is no one single way to get the best surface finish. For example, many engine builders always finish with an 818 stone, but with new plasma-moly rings, which are popular in racing right now, Troutman prefers to finish with a 623 stone. The stone is rougher, but by making his final passes with lighter pressure between the stone and the cylinder wall, the result is a crosshatch that works well with the rings.