Founded in 1901 by brothers John and Charles Reymond in Les Bioux, Switzerland, the company operated as ‘Reymond Frères SA’ until 1929, when it was renamed ‘Valjoux SA’ (short for Vallée de Joux, the‘Watchmaker’s Valley’ where many of the top Swiss brands are still based).

Specializing in chronograph movements, they launched the caliber 22 in 1914; it would remain in production for nearly sixty years. However, it was the smaller 13-line caliber 23, developed in 1916, that revolutionized the world of wristwatch chronographs. It found its way into the timepieces of such prestigious brands as Patek Philippe, Audemars Piguet, Rolex, and Vacheron Constantin.

This movement was produced for sixty years, until 1974. It's estimated that 125,000 of these base movements were made, although relatively few were reworked by Patek Philippe for their chronograph production.