Vintage Rolex-Panerai 3646 at Sotheby’s

Sotheby’s got their hands on an interesting Rolex-made vintage Panerai Ref. 3646 specifically made for German Kampfschwimmers. This watch is part of one of the most fascinating chapters in Panerai’s amazing history. It was first auctioned in 2010 and, as some people pointed out correctly back then, the “original” painted brass dial had been replaced with a so-called California dial.

“Original” is in quotation marks as the original dial the watch was born with in Switzerland and sent to Panerai in Florence, was indeed a so-called California or Error-Proof dial. By reinstalling an Error-Proof dial, the watch was actually just restored to factory specifications.

However, in 2010 the watch did not sell and after the auction it vanished for almost a decade. Now it reappeared at Sotheby’s and interestingly, the “original” painted brass dial is part of the set.

LOT 174 – Panerai/Rolex, Ref. 3646 Stainless Steel Wristwatch circa 1945

Reference: Rolex-Panerai 3646 Type D Kampfschwimmer
Dial: California Dial (plus original painted brass dial)
Case number: 260730 (Type D with low bezel)
Estimate: CHF 40,000 – 60,000

Direct link: LOT 174 – Panerai/Rolex, Ref. 3646 Stainless Steel wristwatch circa 1945 (Sotheby’s)


According to Ehlers & Wiegmann, the famous German author duo, case number 260730 belongs to their Type D typology. In their thinking, watches with same caseback stamps are automatically part of the same group.

The thing is, late Type D watches (260696 – 260849) belong to a later batch than early Type Ds (260400 – 260695). Late Type D watches were produced at a later point in time and came with low bezels and thin California dials. In addition, late Type D watches also have a thinner middle case. All previous batches had high bezels for thick sandwich dials and thicker cases. Another thing that differs is the movement serial number range. Late Type D watches have later movements (7419XXX vs. 7527XXX).

Dial and Hands

Before we go into detail about the dial, I would like to shed some light on the commonly used term California to refer to dials with half Roman/half Arab numerals. Where does this expression originate from?

In Rolex advertisments from the early 1940s, the dial type in question was referred to as Error-Proof dial.

The figures and divisional signs are deeply recessed and filled with strong luminous compound.”

Rolex advertisment from the 1940s (Photo: jojolamontre)

As you can read in the ad, Rolex patented this peculiar dial design. The patent was filled in May 1941 and published under number CH221643 in Aug. 1942.


The patent describes the design as easy to execute and read.

“On constatera que cette disposition donne un tour d’heures clair et simple, facile à réaliser avec de la matière lumineuse et permettant un lecture facile de l’heure surtout pour le boîtes de montres-bracelets dont les cadrans sont relativement petits.
En effets, le fait que les chiffres romains occupent la moitié du cadran et les chiffres arabes l’autre, distingue nettement ces deux moitiés.
En outre, le chiffres romains choisis sont ceux qui sont les plus simple à exécuter et les plus faciles à lire.”

In English: This arrangement creates a clear and simple hours disc, easy to execute with luminous material and allowing an easy time reading especially for wristwatches with relatively small dials.
The fact that the Roman numerals occupy one half of the dial and the arab numerals the other, clearly distinguishes these two halfs.
In addition, the Roman numerals chosen are those that are the simplest to execute and the easisest to read.

The modern Panerai company owned by Richemont uses suggestive language to make-believe Panerai itself created this dial in 1936. The following screenshot was taken from the history section of the Panerai website.


Similar language is used on Instagram. Interestingly, the watch shown by Panerai features a fake dial. On top of that, one look at the distinctive crown tube collar and the short wire lugs makes it evident that the watch shown is without doubt a 3646 from the very last batch from 1944.

I seem to remember Panerai perpetuating the false narrative that the purpose of the peculiar California dial design with half Roman/half Arab indices was to confuse adversaries about the origins of the divers, in case they were captured.

Both claims are of course total nonsense as we have learned from the patent. First of all, there were only two each other opposing forces during WW2, the Allies vs. the Axis. It would not have been very difficult to determine who attacked whom. Secondly, all divers wore regular navy insignia underneath their diving suit and carried an ID card to be identifiable as a member of the enemy force. Men without insignia and/or ID card were considered spies and could be executed on the spot according to matrial law.

No, this dial design, which in may ways can be considered an early version of the iconic Rolex Submariner dial, was developed by Rolex in the early 1940s but it was not until 1944 that Rolex installed them in “Panerai” watches. As you continue reading, you will find clear evidence for this.


Here is the supreme irony. The term California dial was originally used to point out a fake Error-Proof dial.


That’s right! There was a time when Rolex Bubbleback watches with Error-Proof dials were extremely popular in Japan. A dial restorer from California named Kirk Rich started redoing regular Bubbleback dials in sought-after Error-Proof fashion. Since the dials were made in California, collectors used the name of the Golden State to call out fake Error-proof dials. Look, a California dial = fake Error-Proof dial! At some point people forgot what it actually meant and this awful term made it into modern day watch-geek vocabulary.

Basically, the modern Panerai unconsciously chose the correct term for their copied Error-Proof dials.

Coming back to the watch inquestion, let’s have a look at the original Error-Proof dial made by Stern Frères for Rolex.


The following picture shows the back of the present dial. The reference number is ☆ 103 – 2802 and the dial has regular dial feet.


What are dial feet actually? Dial feet are two little pins soldered onto the back of a dial to build a solid connection with the movement main plate. The picture below shows the dial feet in a better angle but is from a different dial.


Let’s have a closer look at the markings on the back. The five-pointed star (far right) is the Stern Frères’s logo. Stern is German for star. The number 103 is a Stern Frères client number aassigned to Rolex SA. 2802 is the reference number for this particular dial model.


This dial is without a doubt original and with reference number 2802, it is clearly part of the 2nd batch of Error-Proof dials made for “Panerai” watches. The first batch with reference number 2731 was faulty and was succeeded by the corrected 2nd batch. More on this later.

As mentioned earlier, the original painted brass dial, which was installed in the watch when it was found, is included in the set. Painted brass dials are not typical Panerai sandwich dials. They are a simplified version made by the Arturo Junghans watch factory in Venice and meant to replace Rolex Error-Proof dials.


As you can see in the picture below, this dial does not have dial feet. How was it attached to the movement without dial feet? Simple. Can you see the notches at 6 and 12 o’clock? They fixed the dial to the movement retaining ring with two tiny screws.


Sotheby’s had the watch dissasemled for proper inspection. The next image shows the movement retaining ring on its own. As you can see, there are holes at 6  and 12 o’clock.


The next picture shows how this type of dial looks like when installed. The tiny screws at 6 and 12 o’clock hold the dial in place.


This is of course not the “horologically” correct way to install a dial. It was merely a hack that became necessary for a very specific reason. Remember I mentioned two batches of Error-Proof dials?

The first batch had reference number 2731 and was faulty. Stern Frères soldered the dial feet in pocket watch configuration instead of wristwatch fashion. The next pictures compares the first batch with the second.


This blunder occured probably due to an error in communication. It can be assumed Rolex forgot to tell the dials were meant for wristwatches. Since the Cortebert caliber 618 was a pocket watch movement, Stern Frères logically assumed, the dials were meant for pocket watches.

The picture below illustrates how the faulty dial with dial feet soldered in pocket watch configuration would have looked like when installed in Ref. 3646.


Interestingly, Rolex did not dispose of these dials. Instead, they removed the incorrectly soldered dial feet and figured out at different way install them.

The next picture shows the back of a reference 2731 Error-Proof dial. As you can see, the dial feet were removed in quite a rough way.


The salvaged dials were then attached to the movement retaining ring with two tiny screws at 6 and 12 o’clock. Sounds familiar?

The next picture shows the front of such a dial where you can clearly see the two notches for the screws.


Unfortunately not a single 3646 from this particular batch that retained the original Error-Proof dial has surfaced so far. Basically, all of these watches were modified with so-called painted brass dials.

Faulty first batch Error-Proof dials with removed dial feet were found at the old Arturo Junghans watch factory during a renovation in the 1990s. Among the things found were also a number of NOS (New Old Stock) 3646 watches with Error-Proof dials and hundreds of painted brass and other dials.

To understand why all this stuff found in Venice and not in Florence where Panerai was located, we need to go back in time.

In July 1943, the Allies landed in Sicily in order to divert German forces from the Russian campaign by opening a second front in Southern Europe. Italy surrendered to the Allies in Sept. 1943 and as a result, most of the Italian peninsula was occupied by German forces. More than 30,000 Italian soldiers were killed within the first hours. Another 700,000 were deported to concentration camps all around Europe. From then on, Italians were considered traitors and lived a live in fear.

In mid 1944, the swiftly advancing British 8th Army reached the outskirts of Florence. Since Panerai equipment such as watches and instruments had become indespenasable for the German war effort, the Nazis raided the G. Panerai e Figlio workshop and confiscated watches, instruments and even machines. Basically everything that was usefull was taken away.

A photographic film box containing a developed film found at the old premises of Panerai in Florence reads:

“Foto dell’officina prima che i tedeschi ci rubassero le macchine.”

In English: Pictures of the workshop before the Germans stole our machines.

Photographic film box (From the book Panerai – Una Storia Italiana, Photo: Luciano Cipullo)

All items stolen from Panerai were shipped to the Arturo Junghans watch factory in Venice. The Lagoon City in the north was firmly in Geman hand behind the heavily fortified Gothic Line, a German defensive line north of Florence. It was not until April 1945 that Venice could be liberated.

If we look at the timeline, it becomes evident Error-Proof dials were only introduced in 1944. There are only two versions of Error-Proof dials found in “Panerai” watches. Ref. 2731 and ref. 2802. Since the first batch was faulty, they made a new batch with correct dial feet position bearing a later reference number (2731 vs. 2802).

The modern Panerai’s claim the very first prototypes from 1936 were equipped with California dials is nonsense. Rolex developed this design in 1941 and had it immediately patented.

Let’s have a look at the hands now. The present watch features skeletonized heat blued steel hands with radium lume. The blue colour was achieved by heating up the metal to a certain degree. This was done as a method to prevent the hands from rusting too quickly.


It is unknown whether the lume is the original one. As you can see in the picture above, the lume was usually applied from the back.

Case and crown

The case of the present watch appears to be in a good shape for its age. There are visisble scratches and dents, especially near the wire lug at approx. 4:45.


The back of the case, including the outside of the caseback, seem ok too.


The profile view shows the watch is extremely thin. As mentioned earlier, watches of this batch have a lower bezel since no extra space was need for thick Panerai sandwich dials. Normal Type D middle cases (260400 – 260695) have a height of 6.3 mm. This case appears to be thinner at first glance.


A quick and dirty measurement reveals the middle case of the present watch is considerably thinner than a regular Type D middle case. The actual height is 5,4 mm.


The next comparison shows the difference in height between a regular Type D watch and the present piece.


Watches from this batch can definitely not be considered to be part of the Type D group since only the caseback stamps are the same.

The inside of the caseback bears typical Rolex caseback stamps which appeared on most Rolex Oyster watches produced between 1938 and 1945. The case number 260730 is a Rolex Oyster case number from 1943/44.


There is at least one watchmaker mark visible which is an indication for a service in the past.

The present watch is missing the original onion-shaped Rolex Oyster crown No. 11. The crown which is installed is an original Rolex Oyster crown No. 13, a typical service replacement for the onion-shaped crown.


The Movement

The engine of this watch is absultely matching with the rest of the watch and appears to be in a great condition for its age.


A look at the serial number reveals the exact movement type: Rolex Cal. 618 Type 1c with 17 jewels made by Cortebert in 1944. This type of movement belongs to the 3rd batch of Cal. 618s specifically made for the use in Ref. 3646.


Ratchet and crown wheel have retained their beautiful swirl finish. The Rolex engravings on the train gear bridge are still filled with the original colour.


This picture of the open watch shows some pitting (corrosion) in the area where the lead gasket touched the case. It is possible the pitting was caused by unremoved seawater.


The present watch is undoubtly a historically important piece made in the middle of precipitating events. For some reason, Panerai was no longer able to produce their signature aluminium sandwich dials. When a new order of watches had to be made, Panerai asked Rolex to include a luminous dial of their own. The Error-Proof dial was Rolex most luminous dial in those days. This was the very moment Error-Proof or California dials were introduced in “Panerai” watches. As a matter of fact, watches with Error-Proof dials were 100% made by Rolex without any involvement nor part from Panerai.

Critical voices will object that Rolex did not make these watches themselves and I fully agree. Back in those days, Rolex was not the same company it is today. Back then they were some kind of “general contractor” and every single component of their watches was made by specialized companies such as C. R. Spillmann (Oyster case), Stern Frères (dials), Aegler and Cortebert (movements), etc. This procedure did not only apply to Rolex, basically every Swiss watch company operated in this way. A watch consisting of parts specifically ordered by and produced for Rolex is nevertheless a Rolex.

All watches prior to this late Type D batch (Type A, B, C & early D), were sent to Florence with white transport dials.


Panerai then opened the timepieces and installed their own signature sandwich dials. These watches were equipped with an extra tall bezel that could easily take thick Panerai dials. In contrast to that, the batch to which the present watch belongs, had a low bezel and a thin middle case. This was undoubtly a reduced to the max version of Ref. 3646, made exclusively during the final months of WW2.

The present watch is a witness of a turbulent era. The ultimate restoration would be to find and install an Error-Proof dial from the first faulty batch.

Thank you for your interest


The Panerai Time Machine

Rolex-made Panerai watches of Ref. 3646 from the final batches are witnesses of precipitating events. These watches were literally shaped by historical events. The infographic below shows all vintage Panerai watches in their historical context. Please click the graphic to download the highres version.



One comment

  • So interesting to read about these Rolex and Panerai watches and how and where they installed these components to make up the iconic timepieces. Learning so much! Great work!


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