The only way to detect the chip is to run your finger over the bottom edge of the shade. It is otherwise unnoticable.
One question that I am curious about. Any idea how many were made and how many are still around?
Another peculiarity - the other lamps described mentioned "Pairpoint" being on the base, and. in the recent ebay sale, also on the shade. I haven't found either. However my lamp base and shade are otherwise identical, including "C Durand" signature.