Agree with dc statement. Not only are there fakes, there are also franken watches, redials, watches sold without original bracelets, etc. Important things to know or have with you to at least arrest some of these problems are things like knowing when the watch was made and compare against known list of Rolex serial number to year of manufacture (available on the Internet), being able to bring the watch RSC to check and verified, able to see and read the model number and serial number between the lugs, posting the pictures on forums that specialise in vintage Rolex to get their opinion ( do note that some of the people in these forums are purists and may consider a service dial not original), know what you want to buy, don't rush into buying and if it is too good to be true, well ......