Rolex Serial (Case) Numbers (and Letter Prefix)
One of the most frequently asked questions in vintage watches is: “is my watch in a period correct configuration?”, or simple “what year is my Rolex?” With vintage Rolex, there are several ways to approach this issue. This Basic Post should help you decoding the figures and letters you can find on a vintage Rolex case.
Vintage Rolex serial numbers (also all engravings in the case back and on for movement parts) are hand engraved using a pantograph. The pantograph is a tool where a mechanical linkage is connected in a manner based on parallelograms so that the movement of one “pen”, in tracing an image or in this case number, produces identical movements in a second “pen” in this case engraving stick. If a line drawing is traced by the first point, an identical, enlarged, or miniaturized copy will be drawn by an engraving stick fixed to the other. Therefore watch manufacturer are able to copy miniturazed numbers or engravings based on large template design onto small watch parts.
The following pictures shows template examples that have been sold in the past at Antiquorum:
Prior to the 1950s serial numbers have also been engraved on the outside of the caseback for some watches. For the majority of vintage the serial numbers have usually been engraved between the lower lugs (at 6 o’clock) of the watch case. Reference numbers have usually been engraved at 12 o’clock using.
It is important to note, that Rolex used several pantographs likewise several original base plates. Therefore, in parallel and over time also different employees have operated those pantographs. Therefore the engravings might differ for close serial numbers. Collectors differentiate those in the so called “batches”. Also keep in mind that the reference numbers have been engraved before the serial numbers. that could lead to a different typeface of the numerals.
Examples of Serial Number engravings. Source: jatucka
It’s a “science” based on experience and large database to evaluate if the engraving is original and matching to the specific “batch”. We do not cover this subject in this Basic Post but interested readers can find a first impression of the complexity of this subject here: Read more
Keeping it simple for this post we focus on the translation of the serial numbers into the production year: The following information and tables should be a good place to start decoding vintage Rolex production dates. As always, please feel free to contact me if you have any comments, suggestions or questions.
So let’s start with the decoding of one of the most googled detail of vintage Rolex watches.
Please note that until ca. 1963 only rough estimation exist because Rolex didn’t archive the exact numbers. In any case the following tables shall give you a fairly accurate guidance to read the matching production year of your serial number:
When Rolex reached 1’000’000 serial numbers in 1954 they restarted with zero:
*During 1976 Rolex retained cases to be used as future "Service Cases" bearing serial numbers from late 4'380m to 4'800m.
In 1987 Rolex changed the towards and used a “letter prefix” and 6-digit number, the first letter being used was the “R” (remember this if you read about a “R-Series”). The letters neither followed an alphabetic order, nor did they start on the 1st of January each year – instead they starting at different points within a year once all the 6-digit number had been used. The numbers used where consecutive, therefore the lower the number following the letter prefix is the earlier the production was in that specific period.
Please find following the simplified date table from ca. 1987 until ca. 2010. Feel free to contact me for detailed information of numbers as of 1987, as it would be to complicated to post all details and numbers:
Rolex Serial (Case) Letter Prefix used from 1987 until 2010
Please find following an example of a letter prefix numerals engraving:
Example of a Rolex Cosmograph Daytona Ref. 16520 R-Series. (Source: TSWISST)
Starting in 2005, Rolex “upgraded” the typical engraving by etching the serial number onto the “rehaut” – a flange of material around the dial of a watch below the crystal – also on the 6 o’clock side. As of ca. 2008, Rolex stopped engraving the case between the lugs.
In 2010 Rolex changed the serial numbers again. Until then Rolex used an 8 digits code of randomly generated numbers and letters. Unfortunately this lead to the fact that only Rolex can tell you when your watch was produced. We made the experience that Rolex ADs are usually helpful in providing you with an answer.
Case Back Engravings
Until 1972 besides you shall also find a date engraving inside the watch case back. Usually the the quarter and the year engraved. This example shows a typical engraving following that logic with “5512” which is the watch reference and “III 59” for the third quarter of 1959):
Case back engraving Rolex Ref. 5512 III 59
Usually the case back year will match to the engraved serial numbers year, but be aware, it could also differ for several (non-conclusive) reasons:
- At service case backs of similar references could have been mixed up. We know this from several occasions and back in the days of the watch forums there have been frequently requests to find and trade “matching” case backs.
- Rolex could have produced case backs in batches and used them whenever watches have been assembled. Therefore occasionally case backs could bear one or two older reference number.
- Rolex “re-engraved” unused cases for likewise or succeeding references (e.g. 6239 for 6241), etc. It was not uncommon to not re-engrave the inside case back numbers.
Please also note that the date of sale of your watch might have been many years after the year of production you can depict from this lists. If you are looking for your “birthday” watch you might want to keep that in mind. Bracelet dates of Rolex are discovered in a different Basic Post (link will be shown at launch of the post).