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Sapphire: the quest for transparency

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January 2022


Sapphire: the quest for transparency

Sapphire, used in watchmaking for almost a century, has become a high-tech material in its synthetic form. In an era of transparency, it is increasingly being used in components. Chanel, for example, launched the first sapphire bracelet in 2020. Anthony Schwab, director of Econorm, an innovative company specialising in the treatment of sapphire for watchmaking, reveals the secrets of this prized material.

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ehind the expansion of the use of sapphire in watchmaking, for the watch glass and beyond (case, bracelet), we can find several companies that specialise in sapphire manufacture and treat- ment. Econorm, Sébal, Erma, Stettler and Comadur (Swatch Group) are just a few of the players in the sector.

Sapphire’s arrival on the watchmaking scene dates back almost a century; Jaeger-LeCoultre used a sapphire crystal to protect the dial of the Duoplan as early as 1929. Since 1966, Swiss brand Century has made sapphire watches its core competitive advantage, through its ingenious and distinctive Megalith technique used to fuse two discs of sapphire into one inseparable piece. In 1980, master watchmaker Vincent Calabrese designed a watch made entirely from sapphire for Corum. Its transparency allowed the ingenuity of the Golden Bridge’s baguette movement to be admired.

“Century sapphire” has been the hallmark of the Swiss brand's timepieces since 1966.
“Century sapphire” has been the hallmark of the Swiss brand’s timepieces since 1966.

Since then, the quest for transparency in watchmaking has led to the increasing use of sapphire in the industry. In 2020, for instance, Chanel went so far as to offer an all-sapphire bracelet on its J12, a world first. In 2021, Hublot unveiled its spectacular Big Bang Integral Tourbillon Full Sapphire model.

The quest for transparency in watchmaking has led to the increasing use of sapphire in the industry. In 2020, for instance, Chanel went so far as to offer an all-sapphire bracelet on its J12, a world first.

 Inspired by the energy of electronic music, Chanel's J12 X-Ray Calibre 3.1 is made entirely of sapphire crystal and set with baguette-cut diamonds. In 2020, the brand introduced a full sapphire bracelet for the first time.
Inspired by the energy of electronic music, Chanel’s J12 X-Ray Calibre 3.1 is made entirely of sapphire crystal and set with baguette-cut diamonds. In 2020, the brand introduced a full sapphire bracelet for the first time.

Sapphire and ruby: cousins

“To innovate and refine the treatment of sapphire, you have to start by knowing the raw material perfectly,” stresses Anthony Schwab, the head of Econorm, which has workshops in Gams and Saint-Imier in Switzerland. Sapphire is in fact a type of corundum, the red variant of which is known as ruby. Sapphire and ruby are therefore “cousins”, and both are very common in watchmaking. They are known for their hardness (the second-hardest natural material after diamond), which makes them difficult to machine.

Diamonds through coloured sapphire? That is what Richard Mille achieved with the Gemset Sapphire RM 07-02. Setting elements on sapphire is a real engineering feat requiring a laser operating to the nearest micrometre. This takes twice the time of ceramics or carbon.
Diamonds through coloured sapphire? That is what Richard Mille achieved with the Gemset Sapphire RM 07-02. Setting elements on sapphire is a real engineering feat requiring a laser operating to the nearest micrometre. This takes twice the time of ceramics or carbon.

Corundum is naturally colourless, but it acquires different hues through the presence of impurities. Traces of iron and titanium, for example, provide the blue colour, which is the most common tint in its natural state. Major sapphire deposits are found in southern Asia and eastern Africa.

 Zenith has recently reinterpreted two of its most cutting-edge calibres for display through the transparency of a sapphire case. One is the Defy Zero-G Sapphire whose off-centred dial is handcrafted in a mosaic of meteorite, aventurine glass and grand feu enamel on a gold base. The astronomically inspired finish extends to the movement's cylindrical container, which can also be viewed through the sides of the case. The other is the Defy 21 Double Tourbillon Sapphire, equipped with two independent tourbillons that complete their rotations in 60 seconds for the time-keeping tourbillon, and 5 seconds for the chronograph tourbillon.
Zenith has recently reinterpreted two of its most cutting-edge calibres for display through the transparency of a sapphire case. One is the Defy Zero-G Sapphire whose off-centred dial is handcrafted in a mosaic of meteorite, aventurine glass and grand feu enamel on a gold base. The astronomically inspired finish extends to the movement’s cylindrical container, which can also be viewed through the sides of the case. The other is the Defy 21 Double Tourbillon Sapphire, equipped with two independent tourbillons that complete their rotations in 60 seconds for the time-keeping tourbillon, and 5 seconds for the chronograph tourbillon.

But make no mistake: watchmaking uses mainly synthetic sapphire, produced in most cases by a method developed in 1902 by Auguste Verneuil. The industrial “Verneuil process” creates sapphire drop by drop from alumina powder, which is melted over a hydrogen flame at a temperature of over 2,000°C.

Watchmaking uses mainly synthetic sapphire, produced in most cases by a method developed in 1902 by Auguste Verneuil.

In 2021, Jacob & Co. has released new timepieces from its Twin Turbo Furious collection that feature both a fully transparent sapphire crystal case and a decimal minute repeater, a first in the world of haute horlogerie. This includes the “Bugatti Blue” timepiece, which celebrates the manufacturer of high-performance sports cars.
In 2021, Jacob & Co. has released new timepieces from its Twin Turbo Furious collection that feature both a fully transparent sapphire crystal case and a decimal minute repeater, a first in the world of haute horlogerie. This includes the “Bugatti Blue” timepiece, which celebrates the manufacturer of high-performance sports cars.

Advanced treatments

“Faced with competition from Asia, our partners Timsaph and Sébal, both located in the Jura region, have launched a 100% Swiss sapphire production, which allows us to rely on a local resource to refine our technologies,” notes Anthony Schwab. On the basis of this raw material, Econorm has been producing “functional sapphires” for the watchmaking industry since 2018. They benefit from cutting-edge treatments: antireflective on both sides, UV filters, achromatic, anti-static and hydrophobic. Indeed, untreated sapphire would reflect too much light and the dial would not be clearly visible.

 The case of Hublot's Big Bang Integral Tourbillon Full Sapphire has been reconstructed in its entirety to house the automatic tourbillon movement. The goal: to remove almost all of the visible screws, overhaul the general geometry of the case to integrate it with the sapphire bracelet, and rework the bridges and main plates to give them the illusion of being suspended in space. The bracelet was also a complex challenge: it alone comprises 165 components, 22 of which are made from sapphire.
The case of Hublot’s Big Bang Integral Tourbillon Full Sapphire has been reconstructed in its entirety to house the automatic tourbillon movement. The goal: to remove almost all of the visible screws, overhaul the general geometry of the case to integrate it with the sapphire bracelet, and rework the bridges and main plates to give them the illusion of being suspended in space. The bracelet was also a complex challenge: it alone comprises 165 components, 22 of which are made from sapphire.

As the manager explains: “Functional sapphires are designed to help both the wearer and the watch manufacturer. For example, the addition of an antistatic function will prevent the accumulation of dust during assembly, and protect the watch’s chronometry from the effects of static electricity. The UV filter function preserves the colours of the dial and thus guarantees that customers receive a product that is true to their choice. In a skeleton watch it also avoids premature ageing of the oils, and thus the need for additional servicing.”

A 2-sided anti-reflective treatment of sapphire crystals is a key step to ensure visual performance and high scratch-resistance.
A 2-sided anti-reflective treatment of sapphire crystals is a key step to ensure visual performance and high scratch-resistance.

In addition to watch crystals, the company also supplies dials, cases and even movement components such as sapphire cogwheels.

“Functional sapphires” benefit from cutting-edge treatments: antireflective on both sides, UV filters, achromatic, anti-static and hydrophobic. Indeed, untreated sapphire would reflect too much light and the dial would not be clearly visible.

As early as 2008, De Bethune produced the first sapphire crystal hands, encircled by blued titanium, to be fitted on the DB26QP. On the new Dream Watch 5, far from simply carving the case from a single block of sapphire using the traditional methods, master watchmaker Denis Flageollet endeavoured to adapt the sapphire to the watch's titanium case. The team had to insert no wer than seven different sapphire parts – each crafted with unique curves and proportions – which would then be embedded into the blued polished titanium exoskeleton.
As early as 2008, De Bethune produced the first sapphire crystal hands, encircled by blued titanium, to be fitted on the DB26QP. On the new Dream Watch 5, far from simply carving the case from a single block of sapphire using the traditional methods, master watchmaker Denis Flageollet endeavoured to adapt the sapphire to the watch’s titanium case. The team had to insert no wer than seven different sapphire parts – each crafted with unique curves and proportions – which would then be embedded into the blued polished titanium exoskeleton.

A matter of price

For its R&D, Econorm collaborates with the Swiss Federal Laboratories for Materials Science and Technology (Empa). More than one and a half million sapphire glasses leave the company’s workshops each year, at a unit price ranging from under ten francs to several thousand francs, depending on the complexity of the work (for example, Econorm worked on the dome glass of the Flying T, MB&F’s first ladies’ watch).

Sapphire is increasingly used to reveal the intricacies of complex mechanical movements in “superwatches”. The technical construction of the Louis Moinet Astronef's case is unusual: a sapphire container mounted on an 18K gold frame, openworked lugs and case middle, and a sapphire dome with applied inner bezel ring. Its transparency enables observers to admire a mechanism that required more than three years of research. In all, six distinct elements are in motion: two satellite tourbillons rotating around the dial, as well as their two cages and their two counterweights.
Sapphire is increasingly used to reveal the intricacies of complex mechanical movements in “superwatches”. The technical construction of the Louis Moinet Astronef’s case is unusual: a sapphire container mounted on an 18K gold frame, openworked lugs and case middle, and a sapphire dome with applied inner bezel ring. Its transparency enables observers to admire a mechanism that required more than three years of research. In all, six distinct elements are in motion: two satellite tourbillons rotating around the dial, as well as their two cages and their two counterweights.
The Purnell Escape II Absolute Sapphire is the first double triple axis tourbillon in a full sapphire case with movement bridges and dial in sapphire.
The Purnell Escape II Absolute Sapphire is the first double triple axis tourbillon in a full sapphire case with movement bridges and dial in sapphire.

Its functional sapphire is not just for watches: like many Swiss subcontractors, the company, which has 60 employees, also works for the medical and automotive sectors, and even for the aerospace industry.

Independent watch brand Artya recently introduced a concept of nano-sapphire allowing for the colour of the sapphire crystal case to change. On the Purity Tourbillon Chameleon, the case turns from a deep blue to a translucent green when exposed to artificial light (6500K or above).
Independent watch brand Artya recently introduced a concept of nano-sapphire allowing for the colour of the sapphire crystal case to change. On the Purity Tourbillon Chameleon, the case turns from a deep blue to a translucent green when exposed to artificial light (6500K or above).
Building on the previous Quasar Light and Quasar Azure models, Girard- Perregaux released a new timepiece housed in a clear sapphire crystal case paired with red accents, the Quasar Infrared. The sapphire case is fashioned from a single sapphire disc. Thereafter, the disc is formed, milled and polished to create a smooth, homogeneous surface, free of inclusions. This latter phase alone takes over 200 hours of work and hundreds of operations.
Building on the previous Quasar Light and Quasar Azure models, Girard- Perregaux released a new timepiece housed in a clear sapphire crystal case paired with red accents, the Quasar Infrared. The sapphire case is fashioned from a single sapphire disc. Thereafter, the disc is formed, milled and polished to create a smooth, homogeneous surface, free of inclusions. This latter phase alone takes over 200 hours of work and hundreds of operations.

“Today, the majority of sapphire crystal supplies for the Swiss watch industry come from Asia,” says Anthony Schwab. “We are hopeful that this will change, perhaps as Swiss watchmaking moves upmarket and average prices increase. Demand for our high-tech sapphire crystal should grow. But it’s a shame we have to go through this, because sometimes it comes down to a difference of a couple of francs per unit...”

“Today, the majority of sapphire crystal supplies for the Swiss watch industry come from Asia. We are hopeful that this will change, as Swiss watchmaking moves upmarket and average prices increase.”

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