The Reference 4240 stands among the most celebrated and technically ambitious wristwatches produced by Vacheron Constantin during the postwar period, a watch that concentrated within a case of restrained classical proportions the full complexity of the triple calendar and moonphase complication at a moment when the Swiss watchmaking industry was producing its finest examples of what the mechanical wristwatch could achieve. Conceived during the late 1940s and produced through the 1950s and into the early 1960s, the 4240 has been described by scholars of Geneva watchmaking as one of the manufacture's defining achievements of the mid-twentieth century, a reference in which the rigour of Vacheron Constantin's movement architecture and the elegance of its case design arrived at a conjunction that subsequent decades of production have consistently failed to surpass.

The distribution of the reference across different case materials provides the essential framework for understanding the rarity of the present example. The 4240 was produced primarily in yellow gold, the standard configuration in which the majority of known examples are found. Pink gold examples are documented but substantially rarer, their warmer chromatic character placing them within the category of pieces acquired by collectors of particular discernment who preferred a more intimate and less conventional interpretation of the reference. Steel examples are rarer still, produced in a very small number of pieces and representing today among the most sought-after configurations of the reference among advanced collectors of vintage Vacheron Constantin. The bicolour variant, combining a stainless steel case with 18-karat pink gold claw lugs, occupies a category entirely its own: documented in only a few dozen examples, it is simultaneously the rarest production configuration of the 4240 and the most architecturally distinctive, the articulated claw lugs in pink gold framing the steel case with a formal contrast that is immediately legible on the wrist and unmistakable in its period character. The present example belongs to this exceptional subset, and is accompanied by a certificate of authenticity that formally documents its identity and specification.