Leroy (pronounced “le roah”) is a French watchmaking house with an interesting, but complicated history (see sidebar for details). They made their name in their day for excellence in chronometry. The brand was revived a few years ago, under the giant Festina group, and exhibited in BaselWorld 2014 and 2015. In 2014, we felt the products were lack lustre, so did not bring you coverage. But 2015, they came back with a vengence. Partnering Eric Giroud, they revamped the entire collection, and the subject of our review: the Leroy Chronomètre à Tourbillon is the best example of how far they have come.

Leroy Chronomètre à Tourbillon

L.Leroy History sidebar

Leroy Chronomètre à Tourbillon: white gold case, grand feu dial under a filigree grid made of 18k gold, with “Marie-Antoinette” tapestry motif.

As part of their Osmior collection which is their tribute to the Leroy chronometric heritage, the specifications list sound like a collector’s wet dream. Firstly, the movement Caliber L100 is fully developed and built in the manufacture in Le Sentier. It features a direct impulst on the balance, and a fusée & chain system for constant force, and interestingly an in-house manufactured balance spring with two terminal curves on a tourbillon escapement. This movement is encased in a 41mm diameter gold case (5N red gold, palladium coated white gold or two tone) with a grand feu enamel dial. It is equipped with a power reserve indicator disc rotating counterclockwise over a 300° angle between 11 and 1 o’clock showing magnificently behind an 18k gold filigree pierced screen. The case also features a hinged hunter back adorned with a barleycorn guilloché pattern and a crown activated secret mechanism.

But we get ahead of ourselves. We begin with the case.

The Case

The Leroy Chronomètre à Tourbillon reveals the level of detailing Leroy has taken to produce a special timepiece. The round case is made of 4 parts, a polished bezel, a circular satin brushed case middle, piloshed gadroons and lugs and a guilloché hinged back cover.

The Leroy Chronomètre à Tourbillon caseback showing the guilloché hinged back cover. The “secret” unlocking device to the caseback can be spied just below the crown.

The hinged back cover, also known as the hunter back, is inspired by 19th century Leroy pocket watches, and carries a similar hand guilloché pattern. This back cover is unlocked by a “secret” device on the crown to reveal the Caliber L100 through the sapphire crystal below.

The case is available in red gold, palladium coated (non-rhodiumed white gold and a two tone variation in 950 palladium and 5N red gold.

The use of palladium as a coating on white gold is a rather interesting to the use of rhodium. White gold is made with 75% of gold, which in its natural state at 100% is yellow. The remainding 25% is alloy components which can change the colour of the gold. For example, white gold is made with gold in alloy with either nickel-zinc or palladium-silver, and red gold is an alloy with copper. Rhodium plating is common in white gold made from gold/nickel/zinc alloy. This is because some people develop an allergic reaction to nickle. Rhodium plating also makes the surface look brighter and whiter than the warm hue of un-plated white gold. Its use is common in diamond set jewellery as the bright, white nature of the rhodium makes diamonds look larger. Palladium plating imparts a slightly grey hue to the case, and its use as a plating in a watch case is slightly unusual. As a comparison, some brands, like A. Lange & Söhne and Patek Philippe do not plate their white gold, preferring to use a higher percentage of palladium in their cases.

The Dial

We find the dial to be particularly attractive. Designed to display the hours, minutes, central deadbeat seconds and power reserve, it maintains a dainty look. Very beautiful.

The dial of the Leroy Chronomètre à Tourbillon showing the detail of the 18k screen bearing the motif of Marie Anotinette’s tapestry. The workmanship is very fine, and this design feature provides the dial with an added sense of depth while not taking away its elegance and beauty.

The power reserve is indicated by a rotating disc at the center of the dial, hidden behind a medalion filigree screen. The screen is in 18k gold reproducing the tapestry motif of a snuff box watch made for Marie-Antoinette. This screen is quite beautifully executed and gives some depth to the dial.

The power reserve indicator, being somewhat hidden behind the screen is a nod towards Julien Le Roy’s invention of the à toc watch which features a discrete indication of the power reserve. In the Chronomètre à Tourbillon, this marker is in the shape of a arrow head. The marker is painted on the rotating grand feu enamel disc visible through the screen.This disc rotates counter clockwise on a 300° axis between 11 and 1 o’clock to indicate the 75-hour power reserve.

What remains of the main dial is a chapter ring in grand feu enamel and features champlevé Roman numerals. We find that although the dial description is fully feature rich, the design manages to tie it down into an elegant, whole which totally gells with the royal origins.

The movement: Leroy Caliber L100

Leroy Chronomètre à Tourbillon movement, caliber L100. The movement is quite spectacular visually, with the impression of depth and layering of the movement components creating a breathtaking spectacle. Of note is that all the bridges and cocks of the movement is mirror polished.

The star for us is undoubtedly the movement. The movement is crammed with features, nicely finished in the French tradition and each individually tested and certified by the Besançon Observatory for chronometry. The tests are conducted for the movement in its case for 15 days, and are hallmarked with a Viper’s Head symbol to indicate that it has passed the stringent tests.

We begin with the features. The movement architecture is a pillar based construction where the movement designers have taken a leaf from the books of the 18th century marine chronometers. The time setting mechanism is an example. It is decorated using a Geneva Mast technique to showcase the finesse and geometry of the going train.

The direct impulse escapement of the Leroy Chronomètre à Tourbillon.

The movement features an interesting direct impulse escapement. This is reminiscent to the Duplex escapement developped by Pierre Le Roy in which a patent was received for the self compensating mechanism for thermal variations. The balance is equipped with a mechanism which compensates for the contraction and dilation of the balance spring due to temperature changes. Quite quaint. The use of complex temperature compensating balances came to past when Guillaume invented the nickel alloys Invar and Elinvar, which demonstrated near zero temperature co-efficient of thermal expansion.

The L100 also features diamond impulse pallets to limit the friction and increase wear. The balance itself uses 4 adjustment screws and a spring produced by Manufacture de Spriaux et Echappments (MSE), a sister company belonging to the Festina group. The balance spring is interesting as it features a double terminal curve which is probably a world premiere. The double terminal curves are described in many text books, but as far as we know, it is not been manufactured until now. MSE manufactures the spring with an inner curve and an outer curve. This allows for a “breathing” of the spring, allowing a more concentric expansion and contraction of the spring which is closer to ideal than one. This is an improvement over the standard Breguet or Phillips overcoil. The two curves eliminate any possible disequilibrium known as the “Grossmann effect” (Jules Grossmann 1829-1907).

The balance oscillates at the classical 18,000 bph with a large balance wheel. And the system is fitted on a one minute tourbillon. Nothing has been spared in the finish of the tourbillon, and yet it is not visible from the front of the watch, and only when one opens the hunter case back is the tourbillon visible. We are great fans of this style of discrete tourbillons, preferring it to be functional, and while still beautifully imagined, designed and executed, remains a private pleasure.

The fusée & chain system supplying constant force to the escapement. Note the Malteze Cross arrangement on top of the fusée to prevent the chain from being ripped off when hand winding the watch. The Malteze Cross blocks the barrel from being further wound at a specific point. Visible on left is the jumping seconds wheel which advances one tooth a second and allows the seconds hand to jump one click every second.

A fusée & chain system supplies the balance with a constant force throughout the duration of the power reserve. The chain comprises of 105 links, totalling 16.275cm. This is a rather classical fusée & chain system with a maintaining power mechanism and a Malteze Cross arrangement. The fusée & chain system is common in marine chronometers and pioneered for used in a wristwatch by A. Lange & Söhne in their Tourbillon “Pour le Mérite” in 1994, and subsequently in all the watches which are part of the“Pour le Mérite” collection. We have covered all these watches here, please do a quick search to read our views on them.  Other notable watches equipped with the fusée & chain is the Zenith Academie featured here.

Wrist shot, with the watch strapped on the wrist of current CEO Olivier Muller.

Concluding thoughts

In final analysis, this is a feature rich watch, with a wonderful history. The watch is beautifully designed. The visual design of the case, dial, hands are very well done. As is the conception and layout and finally the execution of the movement is top drawer. Quite impressive for a company seeking a new lease of life on its second year of showing in BaselWorld. To this, we say chapeau chaps. Well done! And we look forward to other interesting projects from Leroy.

Leroy Chronomètre à Tourbillon Specifications 

Movement:

Type de movement Mechanical hand-wound

Dimensions 15 ½ ‘’’ in diameter 35.3 mm)

7.5 mm thick

Shape Round

Jewels 42 in sapphire and 14 in diamond

Power reserve 72 hours

Frequency 18,000 vph (2.5 Hz)

Barrel Variable torque by fusee-chain transmission

Escapement and regulating organ Direct impulse on the balance by one large direct impulse and one small indirect impulse per oscillation

Balance with screws and thermal self-compensating mechanism (patent filed)

13 mm diameter

Guided by an impulse wheel and a winding wheel for constant force

Unlocking lever with 2 diamond pallets

Unlocking adjustable diamond impulse pin

Balance-spring with double terminal curve: 1 inner curve and 1 outer “Breguet overcoil” Phillips curve.

Display:

• Central hours and minutes

• Central deadbeat seconds

• Painted lozenge-shaped power reserved indicator appearing on grand feu enamel disc rotating counter-clockwise over a 300° angle between 11 and 1 o’clock.

Exterior:

Case

• Diameter 41mm

• Thickness 15.26mm

• 18K 5N red gold or non-rhodiumed 18K 150Pd-coated white gold or bicolored 950 Palladium and 5N Red Gold

• Round, four parts including hinged back cover adorned with barleycorn guilloché motif and crown-activated “secret” mechanism

• Circular satin-brushed case middle – polished bezel and gadroons

• Polished caseback and dial fitted with glareproofed sapphire crystals

• Water resistance to 3 ATM

Dial

• Ivory-toned or royal blue grand feu enamel in 18K gold base

• Satin-brushed or polished champlevé 18K gold Roman numerals

• 18K gold chased grid adorned with “Marie-Antoinette” tapestry motif, placed above the power-reserve indicator disc

• Power-reserve indicator disc rotating over a 300° angle between 11 and 1 o’clock

• Steel Leroy hands in rhodium, 5N gold or anthracite, or blued

• Transferred railtrack taupe-coloured (for ivory-toned dial) or ivory-toned (for royal blue dial) chapter ring

Strap

• In hand-sewn brown, black or blue alligator leather with large square scales and hand-sewn alcantara lining

• Pin buckle or double-blade folding clasp in 18K white gold or 5N red gold