The experts' advice for buying and caring for your sharpening tools:
New diamond hones often will have diamond chips stacked on top of each other from the plating process, creating an uneven surface. Take a coffee mug and rub the bottom side up and down the hone a few times to knock those high diamonds off and level the hone's surface.
Don't buy diamond hones that have small holes in the surface through which you can see the colored plastic backing. Buy diamond hones with solid surfaces. They provide 50 percent more diamond abrasives and sharpen more efficiently.
Avoid buying anything labeled "honing" or "sharpening" oil. It's expensive and unnecessary. Drug-store mineral oil does the job for a lot less money and is food-grade safe.
Porous stones that require oil, such as Arkansas or aluminum oxide stones, will get clogged with tiny bits of blade steel over time and should be cleaned periodically. The easiest way to clean them is to rub a little fresh oil into the stone to loosen up the metal and then run a small magnet through the oil. It will pull the metal right out of the surface of the stone.