Introduction
During the late 1980s and early 1990s, IWC enjoyed one of the most innovative periods in its history, producing technically ambitious watches that combined robust engineering with genuine horological ingenuity. Few people were more influential in this renaissance than Kurt Klaus, whose revolutionary perpetual calendar transformed the complication by allowing every function to be adjusted through the winding crown alone. Originally introduced in the Da Vinci Perpetual Calendar in 1985, Klaus's ingenious mechanism became one of the defining achievements of modern watchmaking and remains one of the most elegant perpetual calendar systems ever devised.
Among the rarest expressions of this remarkable calibre is the Ingenieur Perpetual Calendar Jumbo reference 9240. Produced in the early 1990s in extremely small numbers, it combines the legendary calibre 3758 with the rugged engineering of the Ingenieur, retaining its anti-magnetic soft iron inner cage, screw-down crown and case back despite housing one of watchmaking's most sophisticated complications. Crafted in 18k yellow gold and fitted to a matching integrated bracelet, the reference is accompanied by its original glass vial containing replacement century discs—allowing the perpetual calendar to remain accurate for generations to come. It is a fascinating reminder that IWC designed this watch not merely to outlast its original owner, but to become a family heirloom capable of marking the passage of centuries.
Loupe This Scorecard
Grade
M 8.5
Status
Vetted & Approved
Included
Service roll and papers
Est. value range
$15,000 – $25,000
The Details
Brand
IWC
Dimensions
38mm
Model
Ingenieur Perpetual Calendar Jumbo
Movement
Automatic IWC calibre 3758
Reference
9240
Bracelet
18k Yellow Gold integrated bracelet
Year
Circa 1990s
Condition
Excellent
Material
18k Yellow Gold
Included
Roll and service papers
Dial Color
White
THE DIAL
The whitedial presents the perpetual calendar with remarkable clarity, each recessed register framed by polished yellow gold surrounds that add depth and refinement. Golden tritium lume and the moonphase display complete one of IWC's most elegant sporting dials.
THE CONSTRUCTION
Despite housing a full perpetual calendar, the 18k yellow gold Ingenieur case retains its screw-down crown, screw-down case back and protective soft iron inner cage, providing anti-magnetic resistance of up to 40,000 A/m. It is an extraordinary achievement of engineering that preserves the utilitarian DNA of the Ingenieur while accommodating one of horology's most complex complications.
TIMING MACHINE READOUT
This reading was taken (crown down) with a ONEOF Accuracy Boutique Edition timing machine at time of cataloging. It is provided as a courtesy only, and shall not be construed as a warranty or guarantee of any kind. Please refer to our terms and conditions of sale for more information.
Condition
Watch is in overall excellent condition. The 18K yellow gold case shows surface scratches to the bezel and lugs. The case back has light surface scuffs, partially legible hallmarks, and retains well-defined engravings. The dial is in near-mint condition, and all the hands are very clean. It is fitted with an 18K yellow gold bracelet showing light surface scratches to the polished sections and light play between the links. The bracelet is fitted with 37 links, 7 of which are removable, and fits approximately a 7½” wrist. Comes with the IWC service watch roll, service papers, and instruction tag.
Our Perspective
The reference 9240 occupies a unique position within both the Ingenieur and perpetual calendar story. It combines one of Kurt Klaus's greatest mechanical achievements with the understated engineering ethos of the Ingenieur in a package produced in remarkably small numbers. Accompanied by its century discs—ready to carry the calendar well into the twenty-fourth century—it is a watch that embodies IWC's extraordinary ambition to build something not simply for a lifetime, but for generations.
Justin Gruenberg
Co-founder
