The coloring is simply a dye that is added to the phenolic resin to differentiate the grit on the pad. It actually has no usefulness on the pad at all beyond that.
If color is coming off your smoothing pad, the pad itself should still be fine. It just means we used a little too much dye in making the resin for that pad. The diamonds will still be locked into the resin and perform without any issues at all.
If you feel that the disk is not performing correctly, you can send it back to us for testing.