This incredibly rare, yellow-gold 3940, with champagne dial (from 1989) perfectly illustrates why the reference is so coveted. Understated both in styling and case-size, with this example carrying a highly-desirable 'first-series' doré dial. Such dials are more commonly seen on the earliest Beyer-signed 3940s, or variants of the 3940 with exhibition case-backs. With its modest (by today's standards) 36 mm size, and a svelte case matched by a slim, micro-rotor movement, it fits incredibly comfortably on the wrist.

The dial has three registers, with the various functions neatly balanced out. The sub-dial at three o'clock shows the leap-year counter and the months (in German), in a slightly recessed sub-register, giving depth to the otherwise lightly-brushed, gold dial. This style of sub-register is unique to first series dials. In a similar fashion, the months and day/night indicators are placed at nine o'clock. The stunning moon-phase is placed at six o'clock, with the days of the month around it. The gold dauphine hands add a touch of masculinity to what only can be described as a beautiful dial. The overall look is refined and subtle, without compromising functionality. 

Representing the best of Swiss design, the movement itself is no less a technical feat. This example has a solid case back, revealing the fantastic hand-finishing, the Genevian coat of arms and stripes, as well as the off-center, 22k gold micro-rotor. The ultra-thin self-winding movement has been in use by Patek Philippe since the 1970s, and continue to beat at the heart of their modern perpetual lines.

Perpetual calendars are the authoritative complications of calendar watches. When created the in the mid-80s, perpetual calendars were scarce. With it, a standard for all modern perpetual calendars was established. Timeless, elegant and discontinued - the Patek 3940 is an investment for life, to be worn - and appreciated, daily.

Viewings can be arranged in Central London by appointment.

Closer look