One question in mechanical watchmaking divides opinion perhaps more than every other (except maybe “can a quartz movement be used as the soul of a watch?”): can so-called new materials be used in traditional watchmaking?

Patek Philippe is unquestionably one of the most traditional manufacturers in the world of haute horlogerie. And until the turn of the new millennium, the Geneva icon utilized nothing but metal and synthetic ruby in its movements. However, this most traditional manufacturer has answered the above-mentioned question for itself in a positive manner.

The watch industry – with great thanks to a research consortium that included Patek Philippe – as a whole turned to the use of silicon in 2001, with Ulysse Nardin (also part of the consortium) introducing the game-changing Freak that year.

The millennial collaboration between Patek Philippe, Ulysse Nardin, the Swatch Group, Rolex, and CSEM (Swiss Center for Electronics and Microtechnology) along with its IMT (Institute of Microengineering) in Neuchâtel and the EPFL (Swiss Federal Institute of Technology) in Lausanne bore fruit: each of these companies has continued along its own path in terms of production and use of silicon.The result at Patek Philippe was the founding of its Advanced Research department.

Silicon, long in use as a material in the electronics industry, has proven its many advantages for mechanical watchmaking: it is 60 percent harder and 70 percent lighter than steel; non-magnetic; resistant to corrosion and shock; generally needs no lubrication; can be used to manufacture components with extremely precise geometry within tolerances of one-thousandth of a millimeter.

These qualities motivated Patek Philippe to send out a press release in 2005 declaring that, “Silicon is the fabric of the future.”

2005: Patek Philippe Reference 5250 Advanced Research

While Ulysse Nardin chose to release its Freak very early in the history of the watch industry’s silicon era, Patek Philippe waited four more years, carefully testing and verifying its findings before the company was satisfied the material could live up to its high standards.

Patek Philippe Reference 5250, the brand’s first watch containing silicon

In 2005 it introduced its patented Silinvar, whose name is a contraction of “silicon” and “invariable.” This silicon with an oxidized surface for thermal stability is one that Patek Philippe first used in 2005 for the escape wheel in automatic Caliber 315, which powers the Reference 5250 annual calendar.

The Silinvar escape wheel in Patek Philippe’s Reference 5250

The mass of this Silinvar escape wheel was less than two-thirds that of a conventional steel wheel of the same dimensions, which means it required less energy for acceleration, leaving more energy for the timekeeping operations.

Patek Philippe Caliber 315 Advanced Research with Silinvar escape wheel

Important for Patek Philippe at the time, Silinvar did not change the brand’s access to the Geneva Seal, whose paragraph 8, article 3 at the time read, “The escape wheel must be light, its materials thickness must not exceed 0.16 mm in large parts or 0.13 mm in small parts with a diameter less than 18 mm, its locking faces must be polished.” The locking faces of the Silinvar escape wheel were even substantially smoother than those of a polished steel wheel.

Further reading: Point Of Reference: The Standards Of The Geneva Seal

Quick Facts Patek Philippe Reference 5250 Advanced Research
Case: 39 mm, white gold, sapphire crystal case back with magnifying “bubble” over the escape wheel
Movement: automatic Caliber 315 Advanced Research with Silinvar escape wheel, 21-karat gold rotor with zirconium ball bearings, Seal of Geneva
Functions: hours, minutes, seconds; annual calendar with day, date, month, moon phase
Limitation: 100 pieces

2006: Patek Philippe Reference 5350 Annual Calendar Advanced Research

One year later, Patek Philippe dug a bit deeper with a new Advanced Research model: pink gold Reference 5350, whose automatic Caliber 324 S IRM QA LU was outfitted with a silicon escape wheel and a patented Spiromax balance spring made of Silinvar.

Patek Philippe Reference 5350 Annual Calendar Advanced Research

The new balance spring offered its own new advantages: improvement in precision thanks to more concentric breathing; lower mass; reduced sensitivity to gravity and shock; being two-thirds flatter than a traditional Breguet overcoil hairspring while retaining every advantage of the Breguet overcoil.

Patek Philippe Spiromax silicon balance spring

The Spiromax hairspring has been fitted to the majority of Patek Philippe calibers since this introduction.

Quick Facts Patek Philippe Reference 5350 Annual Calendar Advanced Research
Case: 39 x 11.7 mm, pink gold, sapphire crystal case back with magnifying “bubble” over the escape wheel
Movement: automatic Caliber 324 S IRM QA LU with Silinvar escape wheel and Spiromax balance spring, Gyromax balance, Geneva Seal
Functions: hours, minutes, seconds; annual calendar with day, date, month, moon phase, power reserve indicator
Limitation: 300 pieces
Recent auction price: high estimate $50,000, Phillips November 2016

2008: Patek Philippe Reference 5450 Annual Calendar Advanced Research

The third introduction from the Advanced Research department followed in 2008: Reference 5450 paired a Gyromax balance with a Spiromax hairspring and a completely new Pulsomax escapement with an improved silicon escape wheel and pallet lever.

Patek Philippe Reference 5450P

Patek Philippe Caliber 324 S QA

Patek Philippe Pulsomax escape wheel (left) and Pulsomax lever

This movement showed a more than 15 percent energy gain thanks to the improved geometry of its escape wheel and pallet lever and also allowed for extended service intervals.

Quick Facts Patek Philippe Annual Calendar Advanced Research
Case: 39 x 11.7 mm, platinum, sapphire crystal case back with magnifying “bubble” over the escape wheel
Movement: automatic Caliber 324 S QA IRM LU with Pulsomax escapement (Silinvar escape wheel and lever), Spiromax balance spring and Gyromax balance, 21-karat gold rotor, Geneva Seal
Functions: hours, minutes, seconds; annual calendar with day, date, month, moon phase, power reserve indicator
Limitation: 300 pieces

2011: Patek Philippe Reference 5550 Perpetual Calendar Advanced Research

The fourth Advanced Research model came along in 2011 with Reference 5550: this perpetual calendar debuted another new component in the critical subassembly called the GyromaxSi upon the sixtieth anniversary of the original Gyromax balance. The science-fiction-like part offers a lightweight Silinvar body structure with two 24-karat gold rims and four gold poising screws, which make individualized precision regulation of the rate possible.

Patek Philippe Advanced Research Reference 5550P Perpetual Calendar

The combination of all three silicon components now made for one solid subgroup warranting a total of 17 patents: Patek Philippe’s Oscillomax. The object of all the research and development that has gone into Oscillomax is accuracy and dependability – characteristics very achievable with the use of silicon.

Movement side of Patek Philippe Reference 5550P highlighting the Oscillomax silicon subgroup

At this edition’s launch at Neuchâtel’s CSEM in April 2011, previous Patek Philippe president Philippe Stern (his son Thierry is now president) announced that the silicon Spiromax balance spring would henceforth become the new standard for and be gradually added to all future Patek Philippe calibers.

Quick Facts Patek Philippe Reference 5550 Perpetual Calendar Advanced Research
Case: 37 mm, platinum with diamond between upper lugs
Movement: automatic Caliber 240 Q Si with Oscillomax silicon balance and escapement, Seal of Geneva
Functions: hours, minutes, seconds; 24-hour indicator; perpetual calendar with leap year indicator and moon phase
Limitation: 300 pieces
Original retail price in 2011: $109,000
Recent auction price: $108,000 (Christie’s, November 2013); HK$900,000 (Phillips, December 2015)

Further reading: Behind The Lens: Patek Philippe Advanced Research Reference 5550P Perpetual Calendar and The Schmidt List: 5 Extraordinary Balance Wheels

2017: Patek Philippe Reference 5650G Advanced Research Aquanaut Travel Time

Reference 5650G, released at Baselworld 2017 in a limited edition of 500 pieces, surprised and shocked collectors and connoisseurs: while choosing the Aquanaut to house this new Advanced Research edition was clever because the sporty model family was celebrating its twentieth anniversary in 2017, it was simultaneously shocking because Patek Philippe had until then put its cutting-edge technology only in classic complication timepieces.

Patek Philippe Ref. 5650 Advanced Research Aquanaut

The second surprise was that this timepiece did not introduce a new Advanced Research silicon-based component as the previous four had done, but rather an innovation in compliant technology; this new subassembly replaces the conventional time zone setting mechanism, reducing that subgroup from 37 individual components to 12. The compliant stainless steel leaf spring also needs no lubrication. These new components are made using conventional materials with CNC machines, and they are hand-finished.

Patek Philippe’s chair at the University of Neuchâtel was involved in its development, of course. This seemingly delicate invention relies on the elasticity of the materials to replace mechanical joints with pivots and leaf springs. The assembly’s height was reduced from 1.45 to 1.24 millimeters.

Patek Philippe Caliber 324 S C FUS with Spiromax balance spring and Gyromax variable inertia balance

The third surprise – and I may be so bold to say this was the biggest one for me – was the introduction of a dial with a cutaway at 9 o’clock to highlight the new element in the movement. This sort of design is not usually Patek Philippe’s thing, the brand usually preferring the understated look of a low-key traditional dial regardless of the forward-thinking technology hidden beneath it.

A Patek Philippe silicon component is, however, in evidence in this movement: an optimized Spiromax hairspring (improved center of gravity). It is combined with a classic Gyromax balance with variable inertia rather than the silicon GyromaxSi to complete the balance.

Quick Facts Patek Philippe Reference 5650 Advanced Research Aquanaut Travel Time
Case: 40.8 x 45.24 11 mm, white gold, sapphire crystal case back
Movement: automatic Caliber 324 S C FUS with Spiromax balance spring and Gyromax variable inertia balance, Patek Philippe Seal, 269 components (25 fewer than the previous caliber due to compliant mechanism), max. 45 hours power reserve
Functions: hours, minutes, seconds; date, second time zone
Limitation: 500 pieces
Price: 52,000 Swiss francs