Rob (woodbloke) and I have been using the 10000 grit Spyderco ceramic stone with a lot of success. However one side of mine was very slightly convex across the width, and I decided to flatten with my diamond plate (which is dead flat), this was successful. I next decided to hone a plane iron on the same side that I had flattened and WOW nice dark swarf after just a few strokes. I spoke with Rob he did the same and we both got the same result. It seems that the 10000 stones loads up (this is the term of friends across the pond use) with debris and this reduces the cutting action, we call it glazing. Anyway a few strokes with the diamond stone not only ensures flatness but brings back the cutting action as if new. By the way the others over the pond clean theirs with Ajax and scouring pads, have not tried but I will stick with the diamonds.