About watch case-full sapphire case

About watch case-full sapphire case

Watch cases can be made of many materials. The most common is stainless steel, followed by plastic, gold, trendy materials such as titanium alloy, carbon fiber, and the most special is the sapphire case.

Sapphire has a Mohs hardness of 9, second only to diamond. The main component is alumina (Al2O3). Although it is very hard, it has a crisp texture and is easy to crack. Gem-grade rubies and sapphires can be produced in the laboratory. The chemical composition and physical properties of synthetic sapphire are the same as that of natural sapphire. Sapphire glass is a crystalline form of aluminum oxide (Al2O3), typically containing traces of iron, titanium, vanadium and chromium.

The sapphire crystal generally produced by subjecting aluminium oxide powder under extreme heat and pressure. Further heat treatment removes internal stresses before processing into thin sheets, which make it more durable than standard mineral glass.

Synthetic sapphire glass is second only to diamond in hardness. Diamond is the most hard with its value of 10, it can scratch all other minerals. Mineral glass is around 5-6, and acrylic around 3. The Sapphire glass is 8-9 on the Mohs scale, being nearly unscratchable.

In 2012, the Richard Mille brand launched the RM 056, which used an all-sapphire case, which surprised everyone. However, it was not Richard Miller who first adopted an all-sapphire case, but independent watchmaker Vincent Calabrese, who released his work in 1980. At that time, he designed the famous Golden Bridge movement, which was loaded into a sapphire case in order to facilitate display and promotion. Finally, the watch brand Corum Kunlun took a fancy to it and bought this patented design.

The reason why there is a 32-year gap in the middle is that it is really difficult to make a case made of sapphire material. Its hardness is second only to that of diamonds, and at the same time it is very brittle. It breaks directly without paying attention to it during processing, making the production process extremely difficult. Common sapphire mirrors rely on grinding and are relatively easy to produce. The structure of the case is complex, and it is impossible to process and polish it into transparency with traditional tools. Therefore, polishing a case with a complex structure requires a diamond drill bit and ultra-high speed operation to complete. Therefore, the 1980 Vincent Golden Bridge, the structure and lines of its sapphire case are very simple, and the lugs are still replaced by a metal frame.

It was the Swiss factory Stettler Sapphire AG that was responsible for building the case for the RM 056. It took several years to develop this difficult technology.
The watch media Revolution once interviewed the factory Stettler, revealing that thanks to the advancement of ultrasonic polishing and CNC cutting technology, Stettler has been successfully developed for more than 3 years.

The RM-056 watch, which was published at the Geneva Watch Fair SIHH at that time, was purchased from Russian sapphire.The common sapphire crystal processing technology can only meet the production of watches and mirrors, so the size is not large enough. In order to reach the size of the case, the factory purchased a batch of large sapphire crystals made with a new process from Russia.
Second, cutting. To deal with such a complex case, ordinary processing equipment is simply not capable of it. For this reason, Stettler specially introduced equipment with ultrasonic motors. The most difficult part is to open the hole. They use diamond drill bits to drill at a speed of 10,000 revolutions per minute; the speed of the electric drill can reach up to 40,000 revolutions, but in order to avoid overheating of the drill bit, a lower speed is used.
Finally, polishing. Stettler grinds the cut case with free diamond powder-put the case into a closed device, spray out the diamond powder and hit the surface of the case to achieve the effect of polishing, polishing from 10 microns all the way to 2-3 microns, and finally do chemical treatment, and then apply silicon on the surface.
According to Richard Miller, it takes 1,000 hours to produce such an all-sapphire case.

It takes so much effort because the material of sapphire crystal is too hard but it is also easy to crack. It is easy to make a smooth mirror, and it is difficult to make a case with a complex structure. With the development of science and technology, in just a few years, the case forming process of sapphire crystal has become more and more mature. Sapphire crystal, which was originally completely impossible to carve, can already create a case with a complex structure, and then evolve a variety of colors, and even complete the evolution of hardness and light transmittance.

In fact, synthetic colored sapphire technology was born as early as 1902, but due to the unstable crystallization process, it is difficult to obtain similar-colored sapphire even if it is produced at the same time. In the past, the world has never produced more than 2 kilograms of colored sapphire.

In 2016, Hublot used sapphire cutting technology to create a crystal clear Big Bang Unico sapphire watch. In 2017, Hublot once again broke through the limits and launched the Big Bang Unico blue sapphire watch. Hublot warms the raw material alumina (Al2O3) together with iron (Fe) and titanium (Ti) to 2000-2050 degrees Celsius, and then crystallizes into colored sapphire, retaining the sapphire material's ultra-wear-resistant high hardness and completely transparent permeability. The Big Bang Unico red sapphire watch launched at the same time uses the fusion of chromium (Cr) and alumina to create a red transparent sapphire case. In 2019, Hublot also researched and developed a third-generation transparent case: the “emerald” called SAXEM. The full name of this SAXEM material is Sapphire Alumina and rare Earth Mineral. In order to present a unique green hue, transparency and gloss, Hublot watchmaking factory mixes rare earth elements such as thulium, holmium and chromium with alumina, the basic component of sapphire. The resulting material is harder than soft and difficult-to-polish jadeite, and has more gloss than sapphire. In addition, SAXEM material also has other advantages, such as a slight decrease in the hardness of the material, which strengthens the stability of the polishing process, while the cubic crystal structure allows the case to show the same color and saturation from any angle. Marked by Vickers hardness, the new material is a bit lower than the 2000 hardness of sapphire crystal, reaching 1650, but it is still stronger than the extremely wear-resistant high-tech ceramics 1000-1350. The refractive index of the new material is comparable to that of diamonds.

This has to make people lament the power of science and technology and its rolling forward speed of development. It also allowed more watchmaking brands to try this new material, and many futuristic timepieces were born one after another.

Agelocer is also one of the brands trying to use this sapphire crystal case, the entire case is made from plates of sapphire that are first cut from the solid sapphire and then milled and polished down to the correct shape. Limited to 100 pieces, it's worth playing with. Luxury skeleton agelocer full sapphire tourbillon transparent case watch

When using, pay attention to avoid collisions and avoid materials of the higher or the same hardness, such as diamond rings, watches, glass knives, etc. Although it can be reconfigured, due to the characteristics of the case, if you want to change the case, it is generally recommended to send the entire case back together for reassembly.

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