Jaeger-LeCoultre has been distinguished by its mastery of complications

Throughout its history, Jaeger-LeCoultre has been distinguished by its mastery of complications and, for almost a century, this has included timepieces able to display multiple time zones simultaneously. Caliber 948 is a uniquely artistic expression of universal time, combining a world time display with a flying tourbillon that makes a complete circuit of the dial in 24 hours – an allusion to Earth’s rotation on its axis and its orbit around the Sun. In 2024, La Grande Maison presents a new interpretation of the Master Grande Tradition Caliber 948, with a green enamel dial that celebrates the colors of nature and showcases the skills of the Manufacture’s in-house Métiers Rares™ atelier. Set in an 18-carat (750/1000) pink gold case, it is offered in a limited edition of 20 pieces.

The precision of the world’s time zones

As with all measurements of time, the origin of our world’s time zones lies in astronomy: the passage of our 24-hour day is determined by the rotation of Earth on its own axis. However, zones are a relatively recent concept, driven by the need to impose order and precision on international timing. Until the 19th Century, every city determined its own time, based on 12 noon being the time that the sun was at the highest point in the sky. As railway travel developed in the 19th century, this made scheduling impossible and it became clear that standardized timing – the synchronization of clocks within a given geographical region – and global norms were needed.

At the International Meridian Conference in 1884, it was decided that Greenwich Observatory in London (longitude 0°) would be the basis for calculating times around the globe and each of the 24 major time zones would be defined by 15 degrees of longitude. The world’s day would start and end at midnight at the Greenwich meridian and times would be counted east and west from there – hence the terms Greenwich Mean Time (GMT), ante meridian (am) and post meridian (pm).

The Métiers Rares™ atelier: mastery of ancestral crafts

To create the complex and richly colored dial of the Master Grande Tradition Caliber 948, the master artisans of Jaeger-LeCoultre’s Métiers Rares™ atelier united the skills of enameling, guillochage and lacquering. To complete a single example of the dial requires a total of more than 70 hours of meticulous work.

Champlevé – which translates literally as ‘raised field’ – is a noble and ancient enameling technique that originated almost 2,500 years ago. With great skill, the artisan must first carve out depressions in the surface of the precious metal, conforming precisely to the outline of the desired image. These hollow areas are then filled with multiple layers of enamel – fired at very high temperatures after each layer – until they are flush with the original surface. Adding refinement and intrigue, the enameller uses a combination of opaque and translucent enamels to create areas of lighter and darker color that suggest the continents’ different landscapes. The Caliber 948 dial required 10 layers of enamel and represents more than 20 hours of work for the enameling alone.

Lacquering is a lengthy and exacting artisanal process that requires the manual application of multiple layers of coating on the surface to be decorated. It begins with a clear coat of varnish, followed by a layer of color. This is followed by up to 15 coats of translucent lacquer, to add depth and richness – with each coat requiring a precisely controlled drying process. The lacquering is completed by polishing the disc to a perfect finish that attracts the light and amplifies the richness of the color.

A world of time expressed through artistry of rare precision

Measuring just 25.5mm in diameter, the multi-layered dial of the Master Grande Tradition Calibre 948 is a remarkable work of art in miniature. In keeping with world-timer tradition, the center of the dial is dominated by a map of the world as seen from the North Pole. The outline of the continents is cut from a fine plate of 18ct gold and decorated with champlevé enamel. However, unlike the traditional flattened image, this map floats above the main dial plate on a domed skeleton of pink gold formed by the longitudes and latitudes of the Northern Hemisphere. A masterpiece of laser-cutting precision, this complex and delicate domed structure brings lightness and depth to the dial and makes a subtle allusion to the depth and complexity of time measurement.

Beneath the dome, representing the oceans, the dial plate is decorated with blue-green translucent lacquer applied over a wavy guilloché pattern that suggests the movement of the sea.

As on all classical world timers, each time zone is represented by the name of a city, set on a green opaline ring around the central dial. Set outside the city ring are two concentric fixed rings. The inner ring indicates 24 hours, which are marked with applied rectangular indexes and laser-engraved numerals. The outer ring features the minute track, which is a laser-engraved on a background of dark green lacquer that complements the colour of the map and oceans. In a circular aperture to one side of the map, the flying tourbillon appears to float weightlessly above the oceans, spinning in 60 seconds. As the tourbillon makes a complete 360-degree revolution of the dial in 24 hours, the domed map and the city ring turn in unison, mimicking the rotation of Earth on its axis. Thus the right time in every city is always indicated by the hour marked on the city ring adjacent to the city name.

An elegant case for an exceptional caliber

When Jaeger-LeCoultre created Calibre 948, it was the first time that a world-time complication had ever been united with a flying tourbillon. Moreover, the Universal Tourbillon – patented by Jaeger-LeCoultre – makes a complete circuit of the dial every 24 hours, corresponding to the length of a mean solar day. Consisting of 388 components, the automatic movement is an eloquent expression of Jaeger-LeCoultre’s technical expertise, having been conceived, developed and entirely produced within the Manufacture.

Despite its complexity, Caliber 948 has been designed to ensure that the watch is very simple to operate: the time is set with the crown, which synchronizes all of the time zones around the world. On arrival at a new destination, local time is set by the same crown, which moves only the hour hand, in one-hour jumps forwards or backwards, allowing the minutes and seconds to continue running accurately.

With its pure lines and refined proportions, the Master Grande Tradition case is a perfect foil for the complexity of the dial. Comprising more than 40 parts, its convex bezel contrasts with broad bevels on the lugs, and the hollowed-out lug sides add dynamic tension. Different surfaces are microblasted, polished and satin-brushed to maximize the play of light. The warmth of the pink gold is complemented by a dark green alligator strap that matches the dial.

With its magnificent green dial, the new interpretation of the Master Grande Tradition Caliber 948 is testament to Jaeger-LeCoultre’s commitment to uniting artistic creativity and sophisticated mechanics, always maintaining the fine balance between the spirit of innovation and a profound respect for tradition.