Hublot Big Bang Tourbillon Automatic Yellow Neon Saxem: Reflections of a Laser Physicist on ‘Saxem’

In early 2023, Hublot introduced the Big Bang Tourbillon Automatic Yellow Neon Saxem, featuring a case made of a mysterious and rather impressive-looking crystal called Saxem. It looked like an addition to the brand’s extensive line of sapphire watches. But as a retired laser physicist, I wondered: what material was behind that name? Perhaps a special kind of synthetic sapphire?

Hublot Big Bang Tourbillon Automatic Yellow Neon Saxem

Hublot did not invent the synthetic sapphire watch case. The first examples appeared over 30 years ago by the Century Time Gems brand. It is said that they even patented it. Perhaps it was even earlier, but unfortunately, the brand attracts little attention and it is almost impossible to find more information.

In the mid-1990s, Alain Silberstein, designer and founder of his eponymous brand, followed in the footsteps of Century Time Gems. He did not use quartz movements in transparent sapphire watches because Century Time Gems, which specialized in making ladies’ watches, had relied on quartz. Instead, Alain Silberstein offered a mechanical and complicated Tourbillon Sapphire Squelette watch with a transparent 38 mm case made of sapphire – a good size for men’s watches at that time.

Silberstein’s Tourbillon Sapphire Squelette was equipped with the prestigious Nouvelle Lemania tourbillon caliber. At that time, neither Alain Silberstein’s transparent sapphire tourbillons nor Century Time Gems production attracted much attention, and they remained in the status of rare exotics.

RM-056 by Richard Mille

RM-056 by Richard Mille

These watches did find buyers, but they caused far less of a stir than in 2012 when Richard Mille launched the sapphire-cased RM 056 Sapphire Tourbillon Split Seconds Chronograph costing an eye-watering 1.5 million euros.



Richard Mille reinvented the sapphire watch. Then this theme was taken up and multiplied by Hublot, then followed by several other brands that made sapphire-cased watches an eye-catching modern trend.

MB&F HM9 Sapphire Vision Purple

From a marketing perspective, the coolest thing about this story is that neither Richard Mille nor Hublot claimed that they offered practical scratch-resistant watches at a reasonable price. On the contrary, their watches stood out with fantastically and provocatively high price tags and, accordingly, the brilliance and transparency of the super-expensive sapphire case.

All this triggered a race for colored sapphire cases. Brands, especially Richard Mille and Hublot, tried to make sapphire watches in unprecedented hues. Thus, red, pink, blue, yellow, orange, purple, green, brown, gray and even black sapphire watches came on the market.

In 2019, Hublot took a new step with the Big Bang MP -11 Saxem with a bright emerald-green crystal. It looked very similar to a sapphire case, but the brand announced it was a new material called Saxem. Hublot had an explanation ready: the name is an abbreviation for “Sapphire Aluminum oXide Earth Mineral”.

Hublot Big Bang Tourbillon Automatic Yellow Neon Saxem

Few would have been noticed if the story hadn’t continued. A new Saxem iteration appeared in early 2023 – the Big Bang Tourbillon Automatic Yellow Neon Saxem watch with a striking neon yellow case.



So what has Hublot come up with?

As a physicist, it is evident to me that Hublot did not invent this material. Furthermore, it didn’t appear to have been invented for Hublot. The only thing they invented was the resounding marketing of the Saxem name. I believe Hublot agreed to a commercial offer from an inventive supplier.

Scientists, experts in solid-state lasers, developed an alternative to sapphire over fifty years ago. Or rather, an alternative to synthetic ruby, from which the world’s first laser was made. So, yttrium aluminum garnet, better known to scientists as YAG, was the promising alternative to sapphire – or ruby – in laser technology.

Cerium-doped yttrium aluminum garnet – YAG (photo courtesy Earth Art Gems)

Sapphire does not like foreign ions, which produce the laser radiation – their concentration in sapphire is limited because its atomic structure is so rigid and dense. One of the few exceptions is chromium, which in sapphire gives a red color, and red sapphire is also known as synthetic ruby, which is used extensively as jewels watch movements.

I have no evidence, but my guess is that YAG and Saxem are the same thing. But in the grand scheme of things, it doesn’t change the crux of the matter: if it’s not YAG, it’s a similar synthetic crystal that was most likely developed for use in lasers.

In that sense, much more impressive things can be done with yttrium aluminum garnet than with sapphire. For example, it allows the use of a wide variety of additives that can be used to adjust the wavelength of the laser radiation, which was of utmost importance to the scientists.

Therefore, it could also be interesting for a watchmaker, because it’s possible to obtain crystals with beautiful shades of color – and this is likely to be exactly what Hublot has exploited. The high laser quality of the material is reflected in the fact that the doped YAG crystals have a noticeable fluorescence, and their hue can be described as very bright, neon.

Hublot Big Bang Tourbillon Automatic Yellow Neon Saxem

So Hublot offers a watch made of yttrium-aluminum-garnet, for which they came up with the sonorous name Saxem. This word resonates with something close to the word “sex”, which makes sense because a touch of sexuality is never superfluous in a watch. There’s another bonus, though: anyone can make watches from yttrium aluminum garnet, but Hublot has trademarked ‘Saxem’.



Yttrium aluminum garnet has only a slightly lower hardness – half a point on the Mohs scale – than sapphire, the second hardest natural material after diamond, and this is an important specification for the material from which the watch case is made.

In watchmaking, when it is not a question of setting a case with precious stones, only synthetic sapphire is used – for making watch crystals, jewels for the movement, very rarely for mainplate and bridges, and even more rarely for making cases.

Unlike sapphire, yttrium aluminum garnet is a purely synthetic material with no natural equivalent and, from a mineralogical point of view, has little to do with the group of natural minerals called garnets. In terms of hardness, yttrium aluminum garnet is slightly inferior to sapphire, but it has a higher refractive index that makes polished parts shine better than sapphire – Hublot points this out unequivocally when describing watches made of Saxem, for example the Big Bang Tourbillon Automatic Yellow Neon Saxem.

Let’s take a look at this watch. It costs 220,000 euros, which is about twice as much as a “normal” tourbillon of this brand. For example, a similar model from Hublot, the Big Bang Tourbillon Automatic Carbon made of carbon, costs 105,000 euros. This highlights the price of ‘Saxem’.

Back of the Hublot Big Bang Tourbillon Automatic Yellow Neon Saxem

However, the premium for a transparent sapphire case in the Hublot collection is about the same ratio, except for a rare model with a sapphire bracelet, which also clearly participates in the world championship for the title of the most expensive watch bracelet.

Still, it makes a lot of sense for Hublot to offer Saxem watches, which look like a promising alternative to sapphire-cased watches. Even though the price is about the same as the sapphire models, I’m sure that the huge premium will more than cover the cost of using YAG. Oh sorry, Saxem.

I would like to point out that synthetic sapphire is also found in the Big Bang Tourbillon Saxem. It is used for the transparent mainplate and bridges, the dial, the watch crystal, caseback window, and of course for the jewels of the caliber.

A few words about the tourbillon movement, which deserves respect. The in-house automatic caliber HUB6035 features a cantilever tourbillon that is often referred to as “flying”, although that is nothing more than a poetic metaphor. The caliber uses an unusual scheme developed by Girard-Perregaux in 1999 for its automatic caliber GP9600 with three gold bridges.

Hublot Big Bang Tourbillon Automatic Yellow Neon Saxem

What makes this Hublot special is that the micro-rotor of the automatic winding mechanism is placed on top of the winding barrel – you can see it swinging and winding the watch. At the same time, it makes the watch look even more dynamic and attractive when viewed from the dial side, adding to the grandeur of the tourbillon. And this arrangement saves space.

But more importantly, with this layout Girard-Perregaux designers kept the symmetrical structure of the movement. Symmetry is a prerequisite for the design of a caliber with three gold bridges, which was originally wound by hand.

In developing the HUB6035 caliber, Hublot watchmakers used the same construction with a micro-rotor above the winding barrel, however, they changed the architecture to eliminate a minor drawback of the reversed hand fitting.

This is an easily recognizable feature of Girard-Perregaux calibers with three gold bridges, where the hour hand is placed on top of the minute hand rather than on the bottom.

On Hublot’s Big Bang Tourbillon Automatic watches, including Saxem, we find the traditional arrangement with the minute hand above the hour hand.

Girard-Perregaux Laureato Absolute Light & Fire

Incidentally, Girard-Perregaux has also come on the scene with sapphire and yttrium-aluminum-garnet watches. The latter looks like a retaliatory strike. This is most likely not the case, but it makes the situation even more intriguing.

On January 17, 2023, just a week after Hublot introduced the Big Bang Tourbillon Automatic Yellow Neon Saxem, Girard-Perregaux launched the Laureato Absolute Light & Fire with a burgundy case reminiscent of the color of an excellent aged wine. The case is made of the same yttrium aluminum garnet. By the way, Girard-Perregaux does not hide the true name of the material behind an invented marketing moniker.

When this text was almost finished, I received unexpected help from Ian Skellern, to whom I’d like to express my thanks. Curious to learn more about synthetic crystals, he found another possible candidate for Saxem.

Lutécium Aluminium Garnet Scintillation Crystal for LEDs and lasers (photo courtesy Crystro)

It’s a crystal from the synthetic garnet group, with an abbreviation very similar to YAG: Lutetium Aluminum Garnet, or LuAG for short. In the Cerium-doped version, it’s just about perfect for the mysterious Saxem, especially in terms of fluorescence and hardness of 8.4 on the Mohs scale.

Cerium-doped yttrium aluminum garnet – YAG (photo courtesy Smart Elements)

I concur with Ian’s opinion, but don’t completely rule out Cerium-doped YAG (aka Lumogarnet) – google it, it’s neon yellow and beautiful!

As this theme evolves, what can we continue to expect from Hublot and other brands?

The obvious answer is: more models in other colors.

Almost as obvious: women’s watches in bright neon colors, rave style. All of these can be attractive to a female audience.

Slightly less obvious: since watchmakers have already tried yttrium aluminum garnet, why not try your luck with cubic zircon? This is one of the best and most technologically advanced synthetic diamonds.

Not-so-obvious and possibly fantastical answer: transparent watches with a glowing case – ghost watches. Now that would be something!

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Quick facts: Hublot Big Bang Tourbillon Automatic Yellow Neon Saxem
Case and bezel: polished and microblasted yellow neon Saxem
Dimensions: 44mm x 14.4mm
Caliber: Hublot manufacture caliber HUB6035, tourbillon, micro-rotor automatic winding, power reserve 72 hours
Strap and clasp: transparent yellow structured lined rubber strap, CLASP titanium deployant buckle
Water resistance 30 meters
Limitation: 50 pieces
Price: $210,000

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