The DMT D8C 325 is your best bet for an economical diamond lapping plate. The more expensive Shapton is also 325. I have both and the Shapton is a bit more convenient because of the segmented construction. You don't have to worry about stiction while lapping. I lap in the kitchen sink under running water so the stiction on the D8C isn't a problem and it does as good a job as its more expensive counterpart IMHO. Dia Sharp, the maker of the DMT plates, recommends lapping waterstones with no higher a grit than the 325, and under running water. Otherwise you will damage the plate. As for the Shapton glass. I prefer the Naniwa super stones but that is just a matter of apples and oranges.