I've been offered one. The rotary flat top type with coolant. Don't know allot about them except this one has been used for polishing glass, I've seen them used for pre-honing razors. Is it an abrasive stone, or do you use diamond abrasive in the cutting fluid mix? I'm wondering if it might take a bit of elbow grease out of the first polishing cut, or maybe handy for blending to convex.