Look guys, any table using leather pockets is subject to leave scuff marks on the balls, this problem is not limited to just Diamond tables. What I've done in the past as well as what I recommend, is go out and get you a bottle of Kiwi black/brown shoe polish, depending on what color your pockets are. Make sure it's the "Polish" and not the dye or scuff cover polish. When pockets are finished off in just the dye, the dye will come off on the balls when they are fired into the pockets hard. What the polish does is put a wax finish over the top of the dyed leather therefore creating a barrier between the balls and the dye of the leather, which stops the scuffing of the balls. Polishing the pockets with the wax stops the scuffing of the balls plain and simple.
Glen
PS. Make sure to let it dry first before you start firing balls into the pockets again.