My rock wasn't quite flat but the rock cuts well. I couldn't bring myself to buy the lapping fluid at the exorbitant price they recommended, but after much trial and error I found that Simple Green concentrated, undiluted with water, worked very well and didn't rust the stone at all. Hope this helps someone else. The pictures show a ridge in the center of the 1000 grit side with a corresponding indentation on the 300 grit side. I used a stone dry to show a picture to illustrate the point.
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