ROLEX serial number chart
Rolex and Tudor watch cases are stamped with sets of numbers and/or letters between the lugs at twelve and six o'clock.
The reference number is stamped between the lugs at twelve o'clock.
There is a serial number, unique to each watch, stamped between the lugs at six o'clock, that can be used to date the watch (not applicable to modern Rolexes). While there is no official list, the following chart is an approximation of Rolex dates by serial number.