Rolex engraves a unique, 5 to 8 digit serial number to every watch it makes that helps determine the approximate date, or year of production for that particular watch.These sets of numbers, for example 28000 for the year 1926 or Z000001 for year 2006, are inscribed by machine on the side of the watch case between the lugs at 6 o’clock.While it had been relatively easy to ascertain a watch’s approximate age, or year of production using a database of lists assembled over the years, this will no longer be possible with these new random mixed serial numbers (typical samples include “MN72LK22” or “ JH675TR1” ).
Starting about mid-way through 2010, Rolex started to “scramble” the serial numbers.
Although Rolex claims they made this change to reduce the ability to create counterfeits, many collectors suspect that Rolex did this as a way to maintain balance of the market value and give less power to secondhand Rolex dealers to create value scales based on age of the watch.
Also, it helps dealers to be able to hold inventory longer without savvy customers using the aforementioned new-watch-buying tips.
In 2005, however, Rolex began engraving the serial numbers onto the inner rim of the watch, called the “rehaut”, for stylistic reasons.
Beginning in 2010, Rolex stopped following any sequential numbering system or order altogether and now engraves its watches with a randomized, arbitrary unique identifying number.