While it may sound obvious, consulting the documents that accompany the watch is an important way to tell if a Rolex is real. Ideally, an authentic Rolex should be accompanied by a signed certificate of authenticity and a full warranty. This is true even if you’re purchasing a Rolex through a secondary or independent retailer. Of course, original documentation can often be harder to come by if you’re purchasing a vintage piece, but a watch without any accompanying documents is a red flag regardless of age. If you do have a certificate of authenticity, be sure that the serial number listed matches the number on the watch.