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I think it is all the same if the stone is new or not.

if you get enough slurry between your stone and the lapping media it will create suction. Same effect will occur when you have two fine grit surfaces rubbing against each other, it is caused by...

DMT are supposed to be very flat.
If you have a flat granite plot you can do the lapping on it with sand paper.
You need flat stones but not micron precision flat.