All wrist watches have to be anti-magnetic according to ISO 764 or/and DIN 8309. The international standard "ISO 764 Horology-Magnetic resistant watches" defines the resistance of watches to magnetic fields. According to ISO 764 or its equivalent DIN 8309 (Deutsches Institut für Normung - German Institute for Standardization) a watch must resist exposition to a direct current magnetic field of 4 800 A/m. The watch must keep its accuracy to ± 30 seconds/day as measured before the test in order to be acknowledged as a magnetic resistant watch. For more info feel free to read the Annex of ISO 764 which will give you some more information. Depending on the steel used (martensitic, austenitic) you have to look for additional constructions to warrant anti-magnetism, for example an inner cage (explained on the Damasko web site). Or read all about the Si-parts in watches, they aren't prone to magnetism anymore.
4.800 A/m is about 60 Gauss so not so much but the beauty is that magnetic fields weaken quickly as you move away from the source so for normal everyday use it's absolutely ok.
Q3. Your website notes that the escape wheel and lever are made of silicon, but does not specify the material used for the hairspring. Can I inquire what this is made of?
A3. Hairspring is Nivarox, with their own proprietary alloy.
Nivarox hairsprings are alloys of 45% cobalt, 20% nickel, 20% chromium, 5% iron and smaller percentages of titanium and beryllium. The alloy is not immune to magnetism (being made largely of ferromagnetic metals), but the high percentage of chromium does dampen its response to magnetism.
Q4. Following on from the previous question, does Zenith provide a Gauss rating for how magnetically-resistant this timepiece is, given the use of silicon in the escapement?
A5. As you are no doubt aware the whole movement needs to be protected in order to be anti-magnetic, either by a faraday cage or similar.
Something of an evasion of my question, but I understand the brand's reluctance to warrant any skeletonised timepiece as anti-magnetic. Given a Nivarox hairspring with a silicon escapement, I wouldn't be surprised if the Elite 670 SK is more resistant to magnetism than the 4,800 A/m that ISO 764 requires.
All the answers were on the forum, you just had to look
PS. As a Defy Classic Skeleton owner - it's absolutely worth the money. Fit and finish are impeccable, it's very readable for a skeleton and mine runs really accurate. I would highly recommend it.
In my recent research into the Defy Classic Skeleton, I found the Zenith product pages lacking in some technical details that I, as a deeply nerdy WIS, wanted to know. So I reached out to Zenith directly and was able to get some answers, as below. Q1. What grade of titanium is the Zenith Defy...
A forum community dedicated to watch owners and enthusiasts. Come join the discussion about watch collections, displays, watch winders, accessories, classifieds, and more! We welcome all manufacturers including Casio G-Shock, OMEGA, Rolex, Breitling, Rolex and Tudor, Seiko, Grand Seiko and others.