AT 3538-04 Serial Number

I've always had a thing for dive watches, so I was excited to find a minty used AT 3538-04 (titanium and rubber) at the leading watch repair shop here in Austin. No sooner than I got home, however, it occurred to me that I could not find the serial number. I looked and looked, but nothing. Today I got out a loupe and had a close look under bright sunlight. Sure enough, barely visible just over the word "Aquatimer," was the faintest serial number, which matched the number on the warranty card. Although I had no reason to believe the watch was anything but authentic, it was a relief to find those practically invisible numbers.

My question is this: On my other IWCs--all steel--the serial number is clearly visible, even after years of wear. This number on this watch is absolutely invisible to the unaided eye. The watch is, of course, maybe as much as 12 years old, but is this vanishing act typical for titanium cases?

Hi,

To share my experience, I too have had a complete service done on my 3536 Titan, and yes, the serial number was re-engraved onto the caseback. It's now a lot more faint than before.

I'm certain it was re-engraved as the point size of each number is now larger, but definitely fainter :)

I believe titanium models are repolished through a special machine to attain the same microbrille finish on grade 2 titanium models. Grade 2 is purer than Grade 5, but less hard and brittle.

I sent a query to IWC about the disappearing serial number and confirmed that it will indeed be re-engraved when I do the full service. Good to know.

All IWC's also have the serial number engraved on the inside of the case back. With this,regardless of external wear/refinishing, the watch can always be identified in the future.