Gripping the wire really tightly can cause tool marks, particularly with round nose pliers. Try and work out how much pressure is just enough to achieve what you are doing. Try moving the wire and not the pliers. Ergonomic pliers allow you to exert more force with less effort and this can be a problem in marring your work.
With chain maille, having to hold the weight of your work with your pliers while closing rings causes you to use more force. Resting the weight of the work on your bench instead of holding it in the air can help.
These pliers are both new. The one on the left I have filed with a nail board. You can see the sharp angles are gone and the surface feels smooth to the touch.