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 treatment. 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.

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.

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.

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.

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.

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.

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.”

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.

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).

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.

“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.”