Watch In Focus – Jaeger-LeCoultre Master Compressor

When Jacques Cousteau first invented the aqualung in 1942, it revolutionised diving. Bulky suits that had to be completely sealed were no longer necessary, continuous air feeds were a thing of the past and the Self-Contained Underwater Breathing Apparatus (SCUBA) was born.

This revolution meant diving was no longer expensive, giving would-be divers a chance to fulfil their dreams. Diving as a hobby became extremely popular, and so the need for dive proof watches boomed. Although water-resistant watches were available, none could stand up to the increasing water pressure a diver would experience the deeper they went.

All the major manufacturers got on board the dive watch train, spending huge amounts of money developing cases that would cope with a diver’s requirements. As well as water resistance, divers needed timing bezels and good luminosity, and the cases needed to be able to resist the corrosive properties of salt water. For Jaeger-LeCoultre, their first step was not to develop their own case, but to invest in a company run by a little-known man called Ervin Piquerez.

Ervin Piquerez SA (EPSA) was developing a patented case that, rather than resisting the water pressure, used it to compress the case back and crowns, making the seals tighter and water-resistant to a greater depth. EPSA provided cases for many manufacturers, including IWC, Longines, Hamilton, Blancpain and of course, Jaeger-LeCoultre, until they went bankrupt in the mid-70s.

The compressor case was very distinctive—it usually featured two crowns, one of which operated the internal bezel. Because of the compressor technology, screw-down crowns were not necessary, so the winding and operation of the internal bezel were still possible when submerged.

Jaeger-LeCoultre’s 1959 E857 Memovox Deep Sea was the company’s first venture into diving watches and used the EPSA super-compressor case.

The E859 Polaris Memovox Diver followed the Deep Sea in 1963, after limited runs of diving watches with the names, Shark, Dolphin and Barracuda, and incorporated a triple-backed case to stop the alarm being muffled by the diver’s suit. A third crown at the traditional three o’clock was added for the alarm functionality.

Fast-forward to 2002 and, due to improvements in material technology, the compressor case was no longer required to provide credible water resistance. Jaeger-LeCoultre, however, decided to continue the compressor technology with their crowns. Because screw-down crowns are fiddly and the seals perish with time, a different method was engineered to allow both superior sealing and easy use. The trademark compressor crown features a twist-to-lock switch that has become synonymous with Jaeger-LeCoultre.

The Jaeger-LeCoultre Master Compressor range expanded to include sports and diving watches, some with impressive complications. The Diving Pro Geographic not only featured a second time zone indicator and quick selection for twenty-four time zones, but also a mechanical depth gauge. Following the success of the diving collection, a recent collaboration with the US Navy Seals has produced some adjustments to the range to meet the force’s demanding requirements.

Jaeger-LeCoultre diving watches are unique and sturdy pieces of design, and are a perfect match for someone looking for a more left field choice for their collection, particularly if they want a watch suitable for diving.


  • On June the 30th, 2005, Patrick Musimu dived to a depth of 209.6 metres without oxygen wearing his Master Compressor Diving.
  • At the Master Compressor Diving’s maximum rated depth of 1000 metres, it will be experiencing 890kg of pressure from the water above it.

[Note: This is an updated post of a Guest Article published earlier on our website by Gary Robery from]

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