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In 1986, the world was introduced to the idea of a futuristic material: in Star Trek IV: The Voyage Home, ship doctor Leonard McCoy (DeForest Kelley) and chief engineer Montgomery Scott (James Doohan) traveled back in time for a pair of humpback whales, which necessitated building a massive tank to hold them. The pair thus revealed the formula for an innovative new transparent aluminum to barter for some heavy Plexiglas they needed for the tank.

ArtyA Watch Blog Press Quill&Pad Purity Tourbillon Sapphire Case

Whales in ‘Star Trek IV: The Voyage Home’

The concept of transparent aluminum seemed like true science fiction at the time: how on earth could aluminum be made transparent?

The aluminum that we generally use is not pure aluminum. In fact, nearly no aluminum that we can see exists as pure aluminum; it is too reactive with oxygen to stay pure and so is almost exclusively found as an oxide. The aluminum in products that we use every day, therefore, is also not pure, but rather an alloy that has been mixed with other elements to derive certain properties and often covered with a very thin oxide layer due to its reactivity.

Here’s the rub: so far you have probably been thinking of metallic aluminum, but that is not the only way aluminum can exist. Metallic aluminum is very common, but aluminum oxides can form different crystalline structures thanks to differences in how the atomic structure of the oxide occurred. Another main crystalline form of aluminum oxide (Al2O3) is known as corundum, a transparent mineral. If you’re reading this, you probably know it better by its horological name: sapphire crystal.

Colorful forms of corundum – like rubies – are simply aluminum oxides with trace elements that present different properties. So this begs the question: since what we call aluminum is actually an aluminum alloy comprising various elements, wouldn’t an aluminum oxide, namely sapphire, be the literal expression of transparent aluminum? I’d say it is.

Chemistry nerd side note: metallic aluminum (and all other metals) form a crystalline lattice structure when solid, but the arrangement of atoms is different than the crystalline structure that we would associate with pretty gemstones. Atomic structure is what defines every mechanical property of a material on a macro scale, which is what can lead to the carbon being able to create both super-soft graphite and diamonds when in different arrangements.

This means we’ve been using transparent aluminum for thousands of years, we just didn’t know that’s what it was. And now, thanks to modern chemistry and material science, people have developed both artificial sapphire and other ceramic formulations with aluminum (namely aluminum oxynitride) to create the once-thought-fictional transparent aluminum.

All of this is to say that watches using synthetic sapphire for the crystals are actually using transparent aluminum, which would then mean that watches in full sapphire crystal cases are effectively using Star Trek-hypothesized technology for the entire case.

ArtyA Watch Blog Press Quill&Pad Purity Tourbillon Sapphire Case

Enter ArtyA and its new Purity Tourbillon, a stunning watch combining an ultra-minimal skeletonized tourbillon movement with the perfectly clear and super-strong sapphire crystal case, aka transparent aluminum. The brand doesn’t shy away from extreme aesthetics, but the Purity Tourbillon is extreme in a more mainstream way and for that reason I think it has a lot going for it.

ArtyA Watch Blog Press Quill&Pad Purity Tourbillon Sapphire Case

The Purity Tourbillon from ArtyA is a bold expression of style, but vastly different than the direction ArtyA usually takes, which includes pieces with unique materials, finishes, and aesthetics combined in unpredictable ways. The Purity Tourbillon is aptly named because it is truly a distilled piece of watchmaking without excess. The case is the obvious first step as it is a completely transparent block of sapphire crystal, hiding nothing and with minimal details so as to not distract from the movement inside.

The movement is extremely pared back with only a few arched bridges holding the going train and connecting to a flying tourbillon at 9 o’clock. The tourbillon almost seems to float separately from the movement thanks to the single thin arch extending from the main assembly. The movement is symmetrical along the horizontal axis and is fairly well balanced vertically due to the large diameter of the tourbillon.

Since the Purity Tourbillon is all about purity of design and function, it only displays hours and minutes and uses no markers, numerals, or other features to clutter the aesthetic. The tourbillon has a 60-second rotation, but no dial or markers to track the seconds as they tick off.

The only additional design feature is the ArtyA “A” logo on top of the winding mechanism; otherwise the case and movement keep things as clean as can be.

The architecture of the movement is built around circularity as all the bridges either reflect or downright match the shapes of the wheels and barrels. Two mainspring barrels are vertically positioned side by side, flanking the winding stem, and are held by a lower bridge in the shape of a circle intersecting the pivots. This is in turn is held by an upper bridge with indents matching the rims of the barrels, but also follows the circle of the lower bridge so the visual is a set of stacked circles.

Repetition of shape is a solid way to build visual interest with minimal details, allowing the design of the Purity to feel both complex and clean at the same time. The entirety of the aforementioned bridges, barrels, and winding mechanism fall within a larger circle: the main plate. The circularity repetition is much more apparent from the reverse than the front.

ArtyA Watch Blog Press Quill&Pad Purity Tourbillon Sapphire Case GPHG

Once you flip the watch over, you can clearly see the matryoshka-like circles stacked one inside the other holding the entire gear train. This also makes clear how the tourbillon is mounted opposite the bulk of the movement, with the skeletonizing shaped like overlapping circles. A large area could be left open that makes it seem like the structure holding the tourbillon is whisper thin.

Of course, the circle intersects with a smaller circle that is part of the overall movement diameter, rigidly attaching it to the edge of the case. This feature isn’t hidden from the front, but it also isn’t the highlight, allowing a bit of visual mystery since the focus becomes the whirling tourbillon. At 17 millimeters in diameter, and with a trilobed bridge dominating the look, the tourbillon is clearly meant to be the highlight.

ArtyA Watch Blog Press Quill&Pad Purity Tourbillon Sapphire Case GPHG

The movement, crafted by a complication specialist in Switzerland, is the entire point of the Purity Tourbillon. This is why the design of the bridges is so minimal, why the case is made out of completely transparent sapphire crystal, and why no markers or numerals or an extra sapphire crystal ring around the edge have been added. The impression you are supposed to get with this piece is how clean it is and how much isn’t there.

ArtyA Watch Blog Press Quill&Pad Purity Tourbillon Sapphire Case GPHG1 ld.jpg

Coming back to the sapphire crystal case: it really is the component that allows the minimalist skeleton movement to seem as delicate as it does. With no bulky steel or precious metal case surrounding the movement there is no visual weight to the watch. There are barely any components that seem thick enough to give the Purity Tourbillon any heft, and that is confirmed when you hold it.

ArtyA Watch Blog Press Quill&Pad Purity Tourbillon Sapphire Case GPHG

Sapphire crystal is fairly light, and without any real expanse of steel or brass in the movement thanks to its design the watch simply doesn’t have much to feel physically or visually heavy. The choice of sapphire crystal for the case was probably the best decision to achieve the design intent, and it is still pretty rare in the industry. Sure, sapphire crystal cases have popped up more in recent years, but the numbers are still low and they are very expensive.

Once you consider that the case is made from transparent aluminum (technically) then you understand that this watch has a lot going for it, particularly in how little it feels like there is. It also provides fans of ArytA with something different than its regular offerings, which are in and of themselves always very different from each other.

ArtyA Watch Blog Press Quill&Pad Purity Tourbillon Sapphire Case GPHG

In that way, this watch fits perfectly with the history of a brand that has changed things up with every piece, and this one is no different.

It’ll be hard since the Purity is made from sapphire crystal, but let’s break this watch down !

  • Wowza Factor * 9.2 There is a moment where you realize that this watch looks like it shouldn’t weigh anything, and you are wowed extra hard!

  • Late Night Lust Appeal * 92» 902.212m/s2 The strong yearning for this watch begins with the fact that you can never fully grasp it’s shape, so you stay up all night to try!

  • M.G.R. * 65.4 The sheer design of the movement is enough to give this a highly geeky rating, but the large flying tourbillon seals the deal!

  • Added-Functionitis * N/A Everyone should know by now that the coolest watches aren’t always the most complicated and this one fits the bill. Regardless, you can skip the Gotta-HAVE-That cream and just enjoy the near nothingness that is the Purity Tourbillon!

  • Ouch Outline * 9.98 A strained hamstring! It is always crucial to stretch before and after strenuous activity, lest you get cramps, or worse strain something important like your hamstring. Still, I’d gladly walk with a limp from pulling a muscle if it meant I could limp with the Purity Tourbillon on my wrist!

  • Mermaid Moment * It’s so minimal! It’s hard not to fall head over heels when something is so bold yet so minimal, and the Purity is the perfect synthesis of both!

  • Awesome Total * 805 Start with the power reserve in hours (70) and multiply by the diameter of the case in millimeters (46), finally divide by the frequency of the balance in Hz (4) for a clearly translucent awesome total!

For more information, please visit

Quick Facts ArtyA Purity Tourbillon
Case: 46 x 12.5 mm, sapphire crystal
Movement: manually wound Purity Tourbillon caliber with 17 mm flying one-minute tourbillon, 70-hour power reserve, 28,800 vph/4 Hz frequency
Functions: hours, minutes
Limitation: 13 pieces
Price: 120,000 Swiss francs

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