The Tourbillon Sidéral debuted last year to mark Breguet’s 250th anniversary. This year, the brand is celebrating the 225th anniversary of its founder’s best-known achievement: the tourbillon. For this occasion, Breguet released a quartet of new references, among them the Classique Tourbillon Sidéral ref. 7255PT, a 50-piece limited edition in platinum, once again featuring an in-house aventurine enamel dial.

Despite being the brand’s first-ever flying tourbillon, the Tourbillon Sidéral feels somewhat familiar. That’s because its cal. 187M1 is derived from the brand’s original wristwatch tourbillon movement, the cal. 558, released in 1989. That explains the familiar off-centre dial arrangement and full-plate architecture visible through the case back.

Within this lineage, the Tourbillon Sidéral can be considered the spiritual heir and technical successor to the Classique Tourbillon Messidor 5335 released 2007, a watch that seemed to suspend its tourbillon in mid-air. In fact, this mystery tourbillon was driven by a sapphire crystal drive wheel, and its upper pivot was supported by a sapphire crystal bridge.

The Tourbillon Sidéral elevates this concept to its natural conclusion, dispensing with the upper support bridge entirely, resulting in a true flying tourbillon. Unfortunately, the two-armed tourbillon cage itself spans almost the entire width of the opening, and at times resembles an upper support bridge, at least until the eye registers its clockwise motion.

The Tourbillon Sidéral improves much of the rest of the design, too. The Messidor was visually cluttered — its skeletonised design siphoned away some of the attention from its levitating tourbillon. In contrast, the closed dial of the Sidéral intensifies the focus on the brand’s signature regulator.

If I could change one thing about the Tourbillon Sidéral, I would dispense with the dial appliques, which to my eye feel enormous. And despite the fact that they are expensively made of 18k gold, large appliqués like these — especially “Tourbillon” in italics at three o’clock — cheapen the look.

With its platinum case, gold movement, grand feu enamel dial, and richly executed flying tourbillon, the Tourbillon Sidéral is positioned near the top tier of time-only tourbillon watches. The execution is typical Breguet – excellent.

Perhaps unsurprisingly, its retail price of CHF223,000 positions it squarely against watches like the A. Lange & Söhne 1815 Tourbillon with black enamel dial, which was also limited to 50 pieces. Breguet’s quality usually justifies its prices, and the quality does in this case, but the brand doesn’t have the same cachet as its rivals, at least not yet.

The Tourbillon Sidéral debuted last year with a dark blue aventurine grand feu enamel dial, dressed in the brand’s proprietary “Breguet gold” alloy, which is similar in appearance to pink gold. The case work is familiar, with its fluted band, soldered lugs, and press-fit case back. The simple shapes — all circles and straight lines — suit the name “Classique” especially in this compact 38 mm size.

The platinum edition keep everything else the same except the colour palette, with a black enamel dial and a cool-toned rhodium plating for the gold movement bridges and dial appliques.

The dial is now black with green undertones, instead of dark blue, but it is made the same way. Aventurine glass is an increasingly common material in watchmaking, though many such dials are produced in bulk, drilled to size from larger sheets. In contrast, the Tourbillon Sidéral’s aventurine dial is actually fired enamel that adopts the look of aventurine glass, and each dial is created individually using traditional techniques (but with modern equipment).

When the glossy enamel surface is not catching a reflection, tiny flecks of copper resemble the stars of deep space — hence the Sidéral moniker. A black-coated white gold chapter ring is applied on top, flanked by the aforementioned “Breguet” and “Tourbillon” applied wordmarks.

Between the two Sidérals, I prefer the platinum edition, for the simple reason that the more muted colour palette tones down some of the more visually busy areas of the watch, like the “Quai de l’Horloge” guilloche treatment visible through the case back.

The cal. 187M1 is the latest version of a movement platform that has powered Breguet tourbillon wristwatches for more than 35 years. The flying tourbillon architecture is new but the rest of the calibre — even the mystery drive wheel for the suspended regulator — breaks little new ground.

Fortunately, the movement is impeccably constructed and painstakingly decorated. Breguet has made watches with gold movements since its founding era — the legendary no. 160, long-believed to have been commissioned as a gift for Marie Antoinette, is a perfect example.

Today, however, gold movements are rare enough to warrant special mention. F.P. Journe is certainly the most well-known proponent of gold movements, but Roger Smith makes them on request and they’re standard issue at Biver.

The expensive substrate helps justify the obvious effort put into decoration, which includes both “Quai de l’Horloge” guilloché, applied using a hand-operated straight-line engine, and freehand-engraved markings. There’s also a bit of a barley corn motif, cut with a rose engine, on the floating “bridge” for the lower tourbillon support.

Keen-eyed readers will note the brand has cleverly de-risked the production process by machine-engraving the text on the guilloché plate itself, and saving the freehand-engraved text for applied plaques around and adjacent to the tourbillon.

As for the flying tourbillon itself, it’s built to a standard worthy of the occasion and rewards close scrutiny. The blued metallic hairspring is made of Nivachron, an alloy with some of the antimagnetic properties of silicon, and features an overcoil — a feature almost synonymous with Breguet. The brand almost gave up on this type of hairspring in favour of silicon, so it’s nice to see that the overcoil still has a place in Breguet’s future.

The tourbillon bridge is expertly finished, and the kidney-shaped Geneva-style stud carrier is a marker of tradition. The entire floating mechanism is framed with a rhodium-plated gold ring, polished to help illuminate the aperture.

Breguet Classique Tourbillon Sidéral 
Ref. 7255PT/2N/9VU

Diameter: 38 mm
Height: 10.2 mm
Material: Platinum
Crystal: Sapphire
Water resistance: 30 m

Movement: Cal. 187M1
Functions: Hours, minutes, and flying tourbillon regulator
Winding: Manual wind
Frequency: 18,000 beats per hour (2.5 Hz)
Power reserve: 50 hours

Strap: Alligator with folding clasp

Limited edition: 50 pieces
Availability: At Breguet boutiques and retailers
Price: CHF223,000 (prices exclude taxes)

For more information, visit Breguet.com.

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