1990s IWC were a force to be reckoned with, particularly with regard to the Ingenieur. The ref. 9240 (Ingenieur Perpetual Calendar Jumbo on bracelet) is perhaps the most obscure and rare 1990s Ingenieur reference, but also the most technically accomplished. The only text IWC ever penned to describe it was in its product brochure, which began with the line, ‘It is largely thanks to the watchmakers from IWC, who were obsessed with the idea of creating something immortal, that this watch exists in the first place.’ IWC themselves conceived this reference to create something eternal. You know that’s the case when your watch purchase includes a wax-sealed glass vial with century disc replacements spanning three centuries (included here, your great-grandchildren will have to fabricate their own in the year 2600). This is truly an object built with intent to last and be desirable for generations.

Thanks to a truly genius calibre 3758 with architecture by Kurt Klaus, this reference boasts a full perpetual calendar with moonphase all in a case with no external pushers. That’s right, this is a perpetual calendar where all functions may be adjusted through the crown: time, date, day, month, moon phase, year, and century advance. Each day’s mechanical combination that passes by this calibre will never be seen again, it serves to remind one that time is finite and moves only forward. It is also relatively unique for inclusion of a century complication, not often seen. The only adjustment one must make to keep this calendar totally accurate is to the moonphase once every 122 years, or change the century disc in the year 2200.

In the words of Klaus, ‘I made a moonphase pocket watch, a simple calendar. I was lucky because, although most companies would have thought it crazy to produce a mechanical watch at this time, IWC decided to experiment and make a limited edition of the watch. We made 100 pieces, just to see if there was any demand. We presented them at the Basel Fair in 1976 and they sold out in record time. It was excellent motivation to continue developing. The Sales Director Hannes Pantli came to me and said: “Stop with pocket watches, they are out of fashion. Now do the same in a wristwatch.” This was the birth of the Da Vinci Perpetual Calendar.’ That Da Vinci Perpetual Calendar calibre is the very same powering the 9240 here, debuted 5 years later, and wearing a more sporting attire as an Ingenieur. But that’s not all.

Its 37.5mm 18k yellow gold case is able to maintain the rigid standards of the Ingenieur line, thanks to no case alteration for the complication. There’s a screw-down caseback and crown, and as such was still rated to 30 meters of water resistance when new. Perhaps more impressively, it retained the protective soft iron cage capable of 40,000 A/m magnetic resistance despite the complication. Moreover, as this is a product of the early 90s, it sports that desirable combination of both sapphire glass and golden tritium. We particularly love how each subdial register is ringed by an inlay of angled and polished yellow gold. It’s every bit as interesting as the most notable 90s Royal Oaks, Nautilus, and Overseas out there, just that bit more discreet and off the beaten path.

This example presents in excellent overall condition. The dial shows no signs of damage or wear. Tritium applications are all matched and a deep cream tone in person, all pips on dial are still present. The yellow gold case shows light surface wear. Caseback hallmarks are visible, but shallowing slightly. The calibre 3758 was serviced in late 2022 and is running well. Its bracelet is still very tight, light and minimal wear visible.

This watch is modeled on a relatively large 7.7 inch wrist.

• Brand: IWC
• Model: Ingenieur Perpetual Calendar Jumbo
• Reference: 9240
• Size: 37.5
• Year: c. 1990
• Case Material: 18k Yellow Gold
• Movement: Automatic Calibre 3758
• Scope: Watch, Century Disc Vial, Two Spare Links