Often so called "restoration work" covers bluing screws that were originally polished. Simply polishing screws that are scratched, without conserving the original dimensions of the screw, can be detrimental to a timepiece's integrity. Care needs to be taken to maintain original features such as the bevels on a screw head or the relation of the screw head to it surrounding parts. The color of the blue on a part can be critical as well. A rich "watchmaker's blue" may look nice by today's standards but might not be original to the watch. Imperfections in the bluing are a characteristic of its creator and can display a certain skill level or denote a difference in components such as dial foot screws or eccentric studs.
Each original part speaks volumes about its creator, carrying on its surface details of it’s intended value or purpose when manufactured. Some timepieces are finished through and through, displaying the lavish touch of its creator only to the next watchmaker lucky enough to service such a marvelous piece.