I am trying to clean a few stones and not sure the best way to go about it. Just want to get all of the grease off of some of the larger ones. I used dish soap water and a dmt diamond sharpening stone on what seems to be a washita stone and now looks dull and dry. Should I not clean with soap and water, and if not what should I use? Even a couple I cleaned a few weeks ago now look the same way. Dull and colorless. Like to bring back the natural luster and not ruin some of the nicer escher stones and coticules.. Also didn't want to put something on them once clean that will potentially harm them..