Developed in 1929, the Jaeger-LeCoultre cal. 101 is an incredible achievement. It is impossibly tiny, just 14mm long, 4.8mm wide and 3.4mm high. Weighing almost one gramme, it is comparable in size to a matchstick, yet contains 98 parts.

All of the components inside the cal. 101 are so tiny that the tolerances are impractically fine, meaning the parts need to be finessed by hand before assembly.

Evolved from the earlier, and almost as tiny, Duoplan movement, the cal. 101 was developed for exceptionally tiny and refined ladies’ watches, both wristwatches and even ring watches; Queen Elizabeth famously wore one during her coronation. Almost a century later it is still fit for purpose, having been installed in a pair of Joaillerie 101 watches recently unveiled at the Venice International Film Festival.

The cal. 101 (extreme left), and Duoplan (third from left).

Executed in a style that is distinctly 20th century elegance and almost old fashioned today, both the Joaillerie 101 Reine and Joaillerie 101 Feuille are in 18k pink gold and set with diamonds, with the Reine being the simpler of the two. The Joaillerie 101 Reine is a bracelet centred on a tiny dial showing the time, while the Joaillerie 101 Feuille has a leaf-shaped lid hiding the watch face.

As is typical for watches powered by the cal. 101, both have a tiny crown on the case back for both winding and setting the time.

Price and availability 

Prices for both the Joaillerie 101 Reine and Feuille are upon request, but expect them to start at around US$120,000.