A serial number, green sticker, or convincing box proves very little; all three are easy to copy. The useful checks are the movement, case proportions, dial printing, date magnification, and finishing, but a good replica can still fool a photograph.
If authenticity affects the price, have the watch inspected by Rolex or an independent watchmaker before paying. For clarity, every watch sold on this site is a replica, not an authentic Rolex.
