Manufacturer says use diamonds to hone a stone

In "Ask WOOD" in the May 2003 issue, you correctly advised a reader to flatten a dished sharpening stone by lapping it on a diamond whetstone. However, you said that doing this could prematurely wear the diamond stone.
Actually, as long as you use an extra-coarse (220 diamond/60 grit) diamond whetstone, you can successfully flatten almost any water stone or oil stone with virtually no wear on either the diamond or on the nickel it's bonded to.

David G. Powell, President Emeritus, Diamond Machining Technology, Inc.