300/1,000-grit 8" diamond stone, $90

Diamond sharpening stones work great for shaping and honing tools because they cut fast and last a long time. These M-Power diamond stones (yes, they're called stones even though they're actually diamond-covered steel plates) cut faster than most comparable diamond products, so you finish quicker. And you get two grits on one stone - a real value. The 300-grit side helps you shape a blunt or damaged tool edge, and the 1,000-grit side works great for a first honing. You'll still need another finer stone (4,000-grit waterstone or ceramic) to get an ideal cutting edge.

Tested by John Olson, Design Editor