Diary of a Patek Philippe collector – the “sigma” dial (1st aug 2020)

This week, I discovered that one of my watches was rarer than I had expected.

It took some research and quite a bit of time to discover this information. But it has been worthwhile. Now, not only have I discovered something specific to one of my watches, but also I have discovered something that has been somewhat of a mystery beforehand. Specifically, the issue of the “sigma” dial.

Many watch historians have written about the use of the “sigma” mark that appears below 6 o’clock on some watches. Louis Westphalen at Hodinkee did a great review of the “sigma” dials. I do not intend to re-write his already excellent analysis. However, I will borrow some of the useful points that he made. In his opening lines, Westphalen states that “most of the plentiful information you find out there about sigma dials is wrong, plain and simple.” In general, I think Westphalen is correct. There is a lack of concrete facts surrounding the sigma dial.

The “sigma” mark was used by the Federation of the Swiss Watch Industry to designate when gold was used on the dial of a watch, notably the hands and indexes. To be specific, the US patent record states “that the goods are of Swiss origin and contain solid gold up to a certain standard by the Swiss statutory requirements concerning the control of the use of gold and meet standards and quality established by the applicant.”

The “Sigma” dial using the Greek notation.

The group that led the charge in this process was l’Association pour la Promotion Industrielle de l’Or or APRIOR for short.

As Westphalen points out, the APRIOR group was officially formed in 1973. Many experts have therefore concluded that watches dating before 1973 carrying the sigma dial must be “wrong.” Yet, despite the fact that the official formation of APRIOR was not until 1973, the group applied for the trademark patent of the sigma mark in August 1971, with the patent granted in July 1972.

Now, as Westphalen points out, a number of dial-makers also took the initiative of creating sigma dials before the trademark was given an official seal. At any one point in time, there were between 5-9 different members of APRIOR. Dial manufacturers such as Stern and Singer were amongst those supplying dials. So, is it surprising that watches made by Rolex and Patek Philippe carry this sigma dial before 1973?

Absolutely not.

However, many experts believe that watches dating before 1971 should absolutely not carry the sigma mark. It is seen as too early. Such a conclusion by so-called experts is, however, just an assumption. And, as it turns out, an erroneous assumption.

There have been many Rolex watches with serial numbers dating to 1969 that have carried the sigma notation. Are these watches wrong? I think there is an argument to suggest that such watches are perfectly correct and actually have the very first sigma notations, making them even rarer.

Why do I make this conclusion? Well, although it was not until July 1972 that the patent was granted, the US Patent Office states that the sigma trademark was in commercial use from 25th February 1970. This is a crucial piece of information. So, in effect, these early sigma dials are patent pending versions.

There can be several months gap between when a watch is made and when it is sold. It seems entirely plausible to me that some Rolexes manufactured from late 1969 could easily have carried the sigma mark. But I am only guessing here. However, from 25th February 1970 onwards, the hard and documented evidence suggests that these dials were in commercial use.

It is with respect to Patek Philippe, however, rather than Rolex, that my research unearthed a particular and pertinent fact.

I own a Patek Philippe Ref. 570G. Archive papers show that it was made in June 1970. As stated before, a number of experts have suggested that dials from 1970 with sigma notation are incorrect. My Ref. 570G carries a sigma dial. How did that sigma dial get onto my watch? Was it a service dial? A service dial is how many experts explain the phenomenon of sigma dials on Pre-1972 watches. This is wrong.

50 years old in June 2020. Serviced just TWICE!

I did some research into the history of my watch. This is where I was a little lucky. My 570G has been in for service with Patek Philippe on just two occasions, with records clear for both services. One of those services was just 4 years ago when I first bought the watch. Patek Philippe confirmed to me that the dial is completely original to the watch. Never replaced. Never restored. A sigma dial. Born with a sigma dial. In June 1970. Oh yes.

Just one service between 1970 and 2015. This answered another question for me. Namely, the watch looks essentially unworn. My guess, and it is only a guess, is that the lack of servicing between 1970 and 2015 was because this watch saw virtually no wrist time from its prior owners. Like I said, that is just a guess, but it would explain the condition of the watch and the lack of necessary servicing.

Given that the US patent office states that sigma dials were in commercial use from February 1970, is it such a big deal that my 570G from June 1970 has a sigma dial?

The case and dial on this 570G are in pristine condition for a 50yr old!

Actually, yes, I think it is a big deal. Firstly, Patek Philippe have officially stated to me that the dial is completely original to the watch. The US patent office stated clearly that sigma dials were in commercial use from February 1970. Together, this now shows categorically that so-called experts who categorically state that watches from 1970 with sigma dials are “incorrect” are categorically wrong.

Production of Ref. 570 took place between 1938-1972. Thus, very limited scope exists for this reference to have a sigma dial. But there is a narrow window of opportunity between early 1970 to the end of production some time in 1972 when some dial manufacturers used the sigma dial. The vast majority of 570s came in yellow gold. So, the probability of finding a white gold version with the sigma dial is very small. I would guess that very few exist. I would also argue that (and I have done some homework here), my version is possibly one of the very first Ref. 570s to carry the sigma mark.

Ref. 570G is not such a common watch. Owning one with a confirmed sigma dial adds a lot of spice to this watch for me.

So, if nothing else, I am hoping that those experts who state so categorically that sigma dials should not appear before 1972 should now, perhaps, accept that new information is now available. I am also very happy that my Ref. 570G is one which Patek Philippe have now certified as having an original sigma dial. Very happy.