One of the most breathtaking movies I have ever watched is the true-life story The Walk in which Joseph Gordon-Levitt stars as Philippe Petit, who in 1974 walked (illegally) on a tightrope from one of the World Trade Center towers to the other.

The horological version of this has always been the skeleton watch for me. From a technical point of view, it hardly makes sense: watchmakers go to great length to create a reliable, stable, and robust movement, only to have other watchmakers saw away at the parts that lend it those attributes, including the bridges and base plate.

Skeletonizing is one of those instances in watchmaking when form takes over from function, bringing it even closer to being an art form.

Hand-skeletonized and extensively engraved: Patek Philippe Calatrava Squelette Reference 5180/1R-001

In its original articulation, turning a watch movement into a “skeleton” was a laborious work. It required sawing and filing out the pieces of the base plate, bridges, and even other parts that the watchmaker deemed he or she could alter without influencing the structural balance of the mechanics.

What was left was often not more than framework, which would be perfectly finished and in most cases even extensively engraved to bring the appeal of such a watch to an even higher level.

The beginning of a new era in “skeletons”

Skeleton watches have long enjoyed consistent popularity.

Their main appeal is not only the craftsmanship needed to create them, but also the fact that all the parts making up the mechanical movement are visible. This is a timeless attraction, and even perhaps one of the main reasons why the mechanical watch is still around today.

In that way mechanical watches are also unique: I cannot think of another technology that is so distinctly obsolete, yet still supported by a relatively large industry – an industry that not only makes these masterpieces, but innovates so much.

In particular, it is skeleton watches that have benefited greatly from this over the last decade, as watchmakers have utilized new technologies to push them to the next level.

From skeleton to transparency: Angelus U20 Ultra Skeleton Tourbillon

When Angelus rose from the ashes in 2015, the second watch that the brand owned by La Joux-Perret introduced was the U20 Ultra Skeleton Tourbillon (for more see It’s Not What You Think: Angelus U20 Ultra Skeleton Tourbillon).

Movement of the Angelus U20 Ultra-Skeleton Tourbillon

This is quite a memorable timepiece because it approaches the skeleton watch in a unique way: it features a main plate made out of sapphire crystal upon which skeletonized, blued-titanium bridges are screw-mounted, which secure the manual-wind movement’s regulator assembly with flying tourbillon.

The result adds a layer of mystery to the skeleton movement as it seems to be suspended in air – like a levitating fakir you sometimes see on the street holding only a stick. The Angelus U20’s fakir stick is the connection to the crown, which the brand doesn’t hide (how could it as it is a skeleton watch?).

MasterGraff Structural Skeleton: when skeletons become architectural delights

Graff took a similar approach with its recent MasterGraff Structural Skeleton, in which all the bridges and the main plate have been crafted from sapphire crystal. While a very impressive timepiece, I was personally also quite taken by the previous version, which featured a skeletonized structure out of thin tubes secured in strategic places by screws.

Graff MasterGraff Structural Skeleton Black

A very clever move by Graff was to also skeletonize the brand’s signature case. This extends the magic of the skeletonized movement, actually amplifying it.

These watches are of course a far cry from original skeletonized watches. Where once the expertise and steady hand of a master watchmaker was needed to determine what could be cut away, now CAD programs aid in perfecting the designs, and CNC machines execute them.

Old school: Mr. Armin Strom skeletonizing by hand

That doesn’t make them any less special, however, because thanks to this technology we can actually take the next step in the evolution of skeleton watches.

And then there are diamonds: Piaget Altiplano 1200S

If you really want to up the stakes, you skeletonize an ultra-thin movement.

The height of the bridges and main plate on Piaget Caliber 1200D are already reduced to the bare minimum, and skeletonizing them is walking the high wire so to speak.

But for Piaget that wasn’t even enough: the brand also decided to set the movement with diamonds.

Piaget Altiplano 1200S

To set a brilliant-cut diamond, the jeweler needs to make room in the material – white gold in this case – by drilling or cutting. Generally, this is not such a problem as there is enough material to work with, but when it is done on a skeletonized, ultra-thin movement, quite a different spatial challenge becomes apparent.

Automatic manufacture Caliber 1200D is not only a mere three millimeters high, but also set with no less then 259 brilliant-cut diamonds. The movement is further highlighted by a white gold case set with a dazzling array of the sparklers.

The result is a visual spectacle, and also a true testimony of how far the art of skeleton watches has come over the last few years!

Quick Facts Angelus U20 Ultra Skeleton Tourbillon
Case: NPT carbon fiber and titanium, 42 x 10.3 mm
Movement: manually wound Caliber A-250 with flying tourbillon including variable inertia felly balance, sapphire crystal base plate and blued titanium bridges, 90-hour power reserve with one spring barrel, 3 Hz/21,600 vph
Functions: hours, minutes
Limitation: 18 pieces
Price: 66,200 Swiss francs

Quick Facts Graff MasterGraff Structural Skeleton
Case: 46 x 13 mm, pink or white gold with DLC-coated titanium; watch head weighs a mere 46 grams
Movement: automatic Caliber 6, skeletonized, one-minute flying tourbillon; sapphire crystal plates and bridges, 72-hour power reserve
Functions: hours, minutes
Price: approx. 150,000 Swiss francs

Quick Facts Piaget Altiplano 1200S
Case: 38 x 6.10 mm, white gold set with 346 brilliant-cut diamonds (approx. 1.3 ct) and 40 baguette-cut diamonds (approx. 3.2 ct)
Movement: automatic Caliber 1200D, skeletonized, with a gold main plate set with diamonds (259 diamonds, approx. 0.8 ct) and 11 black sapphire cabochons (approx. 0.2 ct) hiding screw heads; platinum oscillating weight engraved with Piaget coat of arms
Functions: hours, minutes
Price: $192,000

You may also enjoy: Give Me Five! 5 Skeletonized Watches That Came Out Of The Closet At Baselworld 2017 From Patek Philippe, Chanel, Graff, Manufacture Royale And Glashütte Original.