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It is not the first time we hear that a timepiece has a sapphire glass. Some people think it is made of real sapphire, others do not really know. Here is finally the explanation you were waiting for.

There is Sapphire and Sapphire glass

Sapphire is commonly the name given to the precious gemstone variety  from  the mineral called Corundum (an aluminium oxide). Most of the time it is blue because of the presence of iron and titanium but color car be variable depending on other complementary mineral.



Because of its hardness, natural Sapphires can be used in many other domains than jewelry. We can find Sapphires in optical components as well in certain wristwatches movement bearings. In luxury watch-making, the watch glass is always what we call a “Sapphire glass”. Does it means that we tool a real big natural Sapphire and cut a little thin piece on it? Of course not. When we talk about Sapphire glass, this means something else. It is what we call Synthetic Sapphire.

The goal for several industries was to create a solid, harder and strong glass that would replace normal sand-glass in specific usages, like plane windows, high-security vehicles, scientific instruments and luxury items like Timepieces. Scientists realized that the Aluminium oxide provides all the resistance to natural Sapphires, so if they could recreate a crystal configuration with the Aluminium oxide, they would be able to create a stronger glass. Thanks to a specific process, a few companies in the USA and in Russia were able to create a perfect crystal. We call it Synthetic Sapphire or Sapphire glass as it is made from pure Aluminium oxide powder.


The crystallization process requires some mastery, and only a few companies in the world have successfully provided the best quality. Today in the world, we produce around 250 tons of synthetic Sapphire. After the production process, we obtain, depending on the size of the production tank, a 200kg huge piece of crystallized Aluminium oxide. We call it “Boule”, like ball in french.


Why a french name? Well, perhaps because it was a french chemist who invented this production process. His name was Auguste Verneuil and he invented the process to produce synthetic sapphire in 1902.

Auguste-Victor-Louis-Verneuil Verneuil-torch-sketch

Synthetic sapphire is industrially produced from agglomerated aluminium oxide, sintered and fused in an inert atmosphere. The key factor is to use very pure material. For perfect transparency we need to have Aluminium oxide as 99,99999% pure minimum. Otherwise it will result on some kind of veil in the glass.


You can watch a movie her made by one of the companies who produces Synthetic Sapphire glass.

So after obtaining a big Sapphire boule, we can then cut it into pieces and make it as thin as we want.


In luxury watchmaking, the protective glass of the timepiece is mostly done with Sapphire Glass. This material has several characteristics that pleases the watchmakers:

  • Very strong material, so prevents against any scratch.
  • A great transparency that allows a better valorization of what is inside the watch
  • In terms of pressure, it also resists to underwater pressure, which contributes to the water resistance aspect.
  • It is a long-lasting material, which is perfect for a watch that you keep, sometimes, over several generations.

Some watchmakers really considered Sapphire glass as a perfect companion. Some timepieces even challenge the possibilities of Sapphire Glass.

Vianney Halter – Deep Space, 3 axis Tourbillon

Great winner of the Grand Prix of Horlogerie – Geneva, Vianney Halter launched an amazing timepiece called the Deep Space. With its 3 axis Tourbillon, this Timepiece is at the state of the art. And to keep this amazing mechanism working in a safe way, a true dome of Sapphire Glass was integrated.


If you wish to read more about this amazing timepiece, please read our review about it here:

So now you know more about synthetic Sapphire and the way we are using it. Last trends about this material: mobile phones! In deed, smartphones around the world get, at one point, nervous and worried about the scratches on our mobile phones. So the next generation of mobile phone will be dressed with true Sapphire glass. Currently, the Apple iPhone 5 has already a protective lens glass made in Sapphire and the rest of the glass is cheaper. We know that the intention of Apple is to move towards Sapphire Glass, as the Californian company already bought for more than 600 million dollars of stocks. So perhaps the next generation of iPhone will have the new protection? Let’s see!


 Info sourced at different brands website and wikipedia. All content is copyrighted with no reproduction rights available.