From Rolex to Omega to Ulysse Nardin watch, anti-magnetism is a performance that many watchmakers like to boast of, almost as much as waterproof or shock absorption. This is enough to show that magnetism is damaging to the watch, but it also makes one wonder: why? 
At the root of the problem lies in the balance spring, a flat coil that sets the frequency and oscillates back and forth to ensure that the escapement transmits the energy of the mainspring to the rest of the watch in a regular manner. The hairspring is responsible for constant walking time and is itself very fragile and most likely to be magnetized.
Most commonly, when the hairspring is magnetized and the coil is brought close, some of the structures are bonded together, the hairspring becomes shorter, the frequency becomes higher, and the time travels faster. The size of the problem depends on the strength of the magnetization. Too close to the phone screen may not have too noticeable effects for a few minutes; Place your watch on a giant speaker and you'll be able to run faster than an Olympic sprinter.
In fact, the error can range from a relatively imperceptible average of 15-20 seconds per day to tens of minutes per hour. If the situation is particularly bad, it may even lock the mainspring and bring the watch to a complete standstill. That's not good.
Of course, this is not the only problem. Magnetization also affects the temperature compensation of the mainspring, so particularly hot or cold weather may impair the watch's timekeeping function. In the case of more complex watches, the questions come in a variety of forms.
A simple watch degaussing tool.
However, this is easier said than done. The magnets of the speaker and motor are relatively large and easy to circumvent; But tiny rare-earth magnets are everywhere: mobile phones, laptops, refrigerator doors. Luckily, it's very easy to solve this problem. There is no need to disassemble the watch, just buy a cheap degausser; Alternatively, if you're still using an older CRT monitor, you can take advantage of its demagnetization feature to bring your watch closer to the screen. Repair, resolve, avoid damage. Obviously, provided that you are not late before noticing a breakdown.
Either way, it's frustrating when a problem occurs, especially if it's been many days before you realize it's wrong. Even if it's simple to solve the problem, wouldn't it be better if it didn't happen at all in the first place? This is what watchmakers have been working on for centuries.
Rolex Milgauss 116400 There are many ways to resist magnetic fields, but the traditional one is a soft-iron inner case. Back in 1884, Chicago's C k.Giles was patented. The soft-iron inner shell protects more delicate components from magnetic fields, which is an ingenious design. However, at that time, there were fewer magnets in the surrounding environment, and this concept did not have much of an impact. It wasn't until the advent of the magnetized radar system in World War II that anti-magnetic watches became a necessity for pilots. In 1948, the British Ministry of Defence commissioned Jaeger-LeCoultre and IWC to produce the legendary MK 11. 
Large Hadron Collider.
Perhaps the most famous anti-magnetic watch in existence is the Rolex Milgauss, which, as the name suggests, is designed to withstand a magnetic field of 1,000 gauss. In 1956, it was developed for the European Particle Physics Laboratory (CERN) with a built-in Faraday cage for protection. Decades later, Rolex is still working with the European Particle Physics Laboratory. Of course, the easiest way to do this is to make sure that the watch's delicate parts are not magnetized. As early as 1846, Vacheron Constantin experimented with this technique by using a palladium hairspring, but it was not until 1915 that the first anti-magnetic pocket watch was successfully manufactured. 
Cover of a Rolex Milgauss brochure from 1960.
Nivarox advertising in the 1950s.
The introduction of the Nivarox hairspring was the greatest leap forward in anti-magnetic technology in watchmaking, a nickel-iron alloy that was more durable than steel in every way, and which soon replaced the former and even spread to affordable watches. Today, Nivarox has become one of the most important hairspring materials, but it is not perfect and still magnetizes, unlike silicon.
Silicon has many precision advantages, is stronger, requires no lubrication, and while it is not as easy to adjust, it is lighter and harder than steel, and it is completely anti-magnetic. In 2001, Ulysse Nardin launched the phenomenal Freak, the world's first wristwatch to use a silicon balance spring. 
It's a great choice, and Omega and other brands within the Swatch Group have embraced the material, and Rolex is no exception, albeit only at the scratch. Silicon** is more expensive than Nivarox, so not all Sellita or Miyota movements are fitted with a silicon balance spring. Materials and properties are constantly evolving, with Rolex Milgauss watches withstanding a magnetic field of 1,000 gauss and the Omega Seamaster Aqua Terra withstanding a magnetic field of 15,000 gauss. It would make one think that this level of protection is necessary for everyday wear, but it is not. 5 Gauss is considered a safe level, and unless the watch is placed in an MRI machine, all that is really needed is a watch that complies with ISO 764 and is resistant to a magnetic field of 60 Gauss. 
Still, for some collectors, the more the configuration and performance, the better. Ready for a light swim? Well, it's best to get an Ultra Deep or DeepSea Challenge. Over-advertising resilience is nothing new, even if it's fundamentally meaningless. (Photo: Compiled by Xu Chaoyang, Home of Watches).