Date codes explained

The Secret Codes of Patek Philippe: Date Codes

Discover the meaning of those mysterious letters

In this ongoing series, you will learn the ‘secrets’ of the world of Patek Philippe. We will explore questions ranging from the logic behind reference numbers, the meaning of import codes, the insanely cryptic system of dial codes, and marks on your Patek timepieces that you never knew were there. For the first installment, I have something short, sweet, and incredibly useful – an explanation of date codes on certificates.

During the second half of the 20th century, Patek Philippe often shared date codes on the bottom of Certificates of Origin to indicate when a watch left the factory and/or distributor. This simple key below unlocks the secret to understanding the dates that were ‘hidden’ on the certificates.

P   0

A   1

T   2

E   3

K   4

H   5

R   6

O   7

N   8

S    9

This key is remarkably useful when looking at early certificates and assessing dates. For example, if the typed date code is PNNT then this means ‘0882’ or August 1982. The first two numbers are the month and the second two numbers the year. Once you have the certificate date, it is fun to compare the dates on the Extracts from the Archives to piece together the early life of a given watch. Usually, you will see the ‘Date of Sale’ on the archive matches the date the certificate left the factory/distributor. But be warned: you’ll often find discrepancies and surprises, reminding us that even the most concrete system has flaws and is open to human error. All good for me though. The year I was born was ‘OK’.


Date codes explained
In this example we have two date codes on the certificate. The top code is the date the watch left the factory (PHOE = 05/73); and the second is for the date the watch arrived at the Japanese distributor (JPOOE = Japan 07/73); and then we see the date of the sale shortly after in 09/73.


Date codes explained
The Date code system: PNNT = 0882 = August 1982. This is the date when this watch left the factory.


Date codes explained
Here we see a date code for the date the watch left the factory (PTSA = 02/91) and the date it was sold to a client in March 1991. The archive states the watch was made in 1990 and sold in February 1991, matching perfectly with the date code on the certificate. Only the archives have the actual date of completion of the watch; this information is not included in the Certificate of Origin, which gives the date the timepiece actually leaves the workshops.

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