Omega has just announced an automatic movement that is resistant to magnetic fields of an unprecedented 15,000 gauss or more, which is equivalent to over 1,000,000 A/m. Typical antimagnetic wristwatches like the Rolex Milgauss (which gets its name from 1000 gauss) and IWC Ingenieur are resistant to 80,000 A/m. 

Omega Aqua Terra Antimagnetic >15,000 gauss

According to Omega, this was achieved by using non-magnetic materials for some parts of the movement, presumably the escapement and balance assembly. Most antimagnetic watches use the simple solution of a soft iron cage surrounding the movement, which remains a stock calibre. This prototype movement has been fitted into the Omega Seamaster Aqua Terra with striking yellow accents, but the actual production piece will be unveiled during Baselworld 2013. These watches containing the Co-Axial calibre 8508 will be available in stores in 2013. Incidentally the last few months have seen a rash of antimagnetic watches announced, from Panerai’s Submersible Amagnetic to the Grand Seiko antimagnetic models. Even Habring2 recently said it is working on an antimagnetic movement with non-ferrous escapement parts. Beyond silicon parts and constant force mechanisms, antimagnetic calibres are a still novel, but fairly simple and cost effective, way to better chronometry, so expect more of them. – SJX