It only wears down the finish if the seals are gritty and wearing the surface. Theirs 0 wear on these stantions, im looking at them now and its still onyx black. Like i mentioned earlier, its a cell phone picture with the sun glareing off them. Note other pictures where theres no marking..

 are the stantions rubbed off

 ok

 its deff rubbing sown all black sanctions do that