It does not matter. I use black or just let them take on their natural lead color if not coated/painted. Fish have no interest in the weight. It's whats attached to the end of the release thats attached to the weight that's important. I've spent many days fishing next to anglers & guides that were using painted, taped or even Shark weights and caught just as many fish as they did using just plain old black or natural lead. It's more of a confidence thing for the angler than anything, IMO..........
Ball weights, pancake weight or a sock filled with gravel, as long as it's heavy enough to do the job will work. If fishing over structure or bouncing bottom, stick weights are the way to go. I use ball trolls if I want to get their attention closer to the weight and don't worry about the color of my balls, "pun intended" PLEASE!!! Good luck, Mark