Though the International Watch Company is most often associated with aviation, the manufacturer from Schaffhausen cemented its global reputation with the Portugieser line, now a flagship collection for the brand and an opportunity to showcase their expertise in manufacturing complicated watches.

The Portugieser had its genesis in the 1930s, shortly before the Second World War. Two clients from Portugal tasked IWC's watchmakers with producing wristwatches that were as accurate as marine chronometers. In those days, the only way of achieving this goal was to take movements from pocket watches and put them in wristwatch cases. 

IWC thus used a Calibre 74 movement as the basis for the new line, christened Portugieser after the homeland of the clients who inspired it. Since the Calibre 74 movement was a hefty 37mm wide, the Portugieser required a large case to match — a huge departure from the slim cases that typified wristwatches of the 1930s.

Though IWC continued to produce the Portugieser line throughout the 1970s, it never was the company’s most profitable or plentiful. But by the 1990s the Shaffhausen-based maison was inspired to revitalize the aging collection, and today, the Portuguese line includes some of the brand’s most lovely and complicated pieces — such as the model we have here.

This particular Portugieser, a perpetual calendar Reference IW503401, is a stunning example of IWC’s in-house watchmaking capabilities. Mechanically programmed for 577 years of accuracy, it’s like a small, mechanical computer on your wrist — though at 44.2mm wide, it certainly makes its presence known!

Housed in an 18K white gold case with a sapphire crystal, a signed crown, and a polished, concave bezel, it features a satin blue dial with applied Arabic indices; recessed subsidiary registers with day, date, power reserve, running seconds, month, moonphase, and year apertures; and a matching ‘feuille’ handset. Visible beneath a sapphire exhibition caseback, the automatic IWC Calibre 52615 movement can be seen doing its thing - with an incredible 168-hour power reserve!  Paired to the watch is a signed, black IWC alligator leather strap made by Santoni fitted to a signed white gold deployant clasp.