Around this same time, Rolex had initiated another dating system--They stamped the inside of the case
back with a code consisting of a Roman numeral and two numbers. The Roman numerals were I, II, III,
IV, which represented which quarter of the year the watch was produced. The numbers simply
represented the two-digit year in which the watch was produced. Therefore, the code III 53 would
represent the 3^rd quarter (i.e. July-September) of 1953--this code continued until around 1970.

In the early 1960s, Rolex once again reached the 999,999 mark, but this time added a 7^th digit and
continued until mid 1987, when the numbering reached 9,999,999. At this time, Rolex elected to start
numbering with a letter prefix (e.g. R000001).

The system started with the letter "R", which was then subsequently followed by L-E-X. Thus spelling
out the word "ROLEX" with the "O" being omitted, to help avert any possible confusion with the number
"0". This sequence continued through November 1991, when a new numbering system was introduced
utilizing the letters N, C and S, which took them through 1993. In 1994, Rolex started yet another
sequence with the letters: W, T and U, then A, P, and K in subsequent years.

To add to the confusion, many of these prefixes have run concurrently over the past few years, giving
the appearance of a random numbering system. Therefore, only Rolex knows exactly when any
particular watch was made and they aren't talking.

 

The following list is comprised of known serial numbers for the years listed. By checking a particular
serial number against this list you should be able to date a watch with reasonable accuracy. However,
it is no guarantee as to when your watch was shipped from the factory. Furthermore, this list only
applies to Rolex Oyster-cased watches.