Watches & Wonders 2024 will see the return of the Rolex Milgauss? As you know, we don't usually make predictions, but what is certain is that Rolex filed a patent last year that promises to raise the price to 40 Gauss the anti-magnetic properties of its watches.

Rolex engineers realized that to increase the current anti-magnetic rating, it was necessary to change the composition of the balance wheel to an alloy that is less conductive to electricity. As can be read in the patent, Rolex said the findings were “surprising and unexpected.” But first, let's look back at the history of the Rolex Milgauss.


The Milgauss represents the result of a close collaboration between Rolex and CERN – Center Européen de Recherche Nucléaire, a nuclear research organization based in Geneva. The common goal was to create a wristwatch that could withstand intense magnetic fields, thus allowing engineers and laboratory workers at CERN to wear it constantly in highly magnetic environments.

The result of this synergy is the Milgauss, whose name derives from the Latin “mille”, meaning thousand, and “Gauss”, a unit of measurement for magnetism, in homage to the German mathematician and physicist Carl Friedrich Gauss. In the 60s, the Rolex Milgauss reference 1019, took the place of the two original versions, references 6541 and 6543 and was produced until 1990 and available exclusively in stainless steel.

The Milgauss makes its return in 2007, with the reference 116400 which took the place of the timeless ref. 1019. Following the same principle as the previous Mil referencesgauss, the movement is protected by a metal cage, a real second caseback. Aesthetically the model paid homage to the ref. 6541, the ref. 116400 with the central second hand in orange color, similar to a “lightning bolt”. Furthermore, what is particularly interesting is that the ref. 116400 is equipped with a green-tinged sapphire crystal, giving the reference a completely unique charm that can be noticed from afar.

16 years later, in 2023 the Milgauss it went out of production to presumably update itself to the new calibers and precision standards that Rolex achieved with the generation of the 32XX movements, but presumably - as you will read - to raise the resistance to magnetic fields to incredible levels.


When tested with the traditional lead-free brass balance wheel, the watch held its own up to 40.000 gauss, instead of 25.000 gauss with a copper-beryllium balance wheel, the alloy in the current collection. The results are “absolutely remarkable,” Rolex said in the patent.

The blue Parachrom hairspring inside the Rolex movements draws all the attention. Its anti-magnetic property ensures maximum accuracy even near magnetic fields, such as those produced by speakers, refrigerators, some bag clips or tablet cases.

But what happens if in addition to the hairspring, changes are also made to another key component such as the balance wheel?

The Parachrom hairspring and balance wheel work together and are mounted on top of each other. In fact, the spiral could not beat its hypnotic rhythm without the inertia effect produced by the balance wheel. The balance wheels are machined from solid bars of copper-beryllium alloy at the Rolex site in Biel. In Rolex laboratories, copper-beryllium is called “cuivre beryllium” in French and abbreviated “CuBe“, as in the periodic table. CuBe has some anti-thermal and anti-magnetic properties.

But Rolex engineers recently made a discovery. When they changed the league from CuBe to an alloy with more insulating properties, i.e. an alloy that is less conductive to electricity, they were able to increase the anti-magnetic rating of the watch beyond all expectations.

“Surprisingly and unexpectedly increasing the resistance of a metallic material is very important in increasing the magnetic threshold,” Rolex wrote in its patent filing with the Swiss Institute of Intellectual Property.


In their tests, Rolex engineers used a superconducting electromagnet that created a magnetic field with an intensity of the order of 10 tesla, or 100.000 gauss, and they increased the power. They exposed the watch for 20 minutes at each setting, 0,25 tesla at a time.

In tests involving movements currently in production, with balance wheels made from CuBe, Rolex watches were able to withstand between 22.500 gauss and 25.000 gauss. This is important information, as Rolex has never officially declared the resistance to magnetic fields of its watches.

In the second series of tests, Rolex tested movements with balance wheels made of lead-free brass, called “Ecobrass”. And that's where Rolex engineers were amazed.

"Changing the balance material had an unexpected and surprising effect. Lead-free brass has a higher resistivity than CuBe commonly used for balances and sinkers,” reads the patent.

Tests revealed that Rolex engineers managed to increase the power up to 4 tesla, or 40.000 gauss, before seeing any negative effects on accuracy of the clock. “The only limitation in this configuration was observed after exposure to 4 T,” the patent said, using the tesla unit of measurement. “Which is absolutely remarkable.”

It's unclear whether these innovations will find their way to Watches and Wonders in 2024. But one thing is for sure, Rolex's innovative spirit will take watches' resistance to magnetic fields to the next level! It will be the new Milgauss, the first model resistant to 40 gauss?