The latest in Piaget’s ever growing continuum of progressively slimmer watches, the Altiplano Ultimate Concept is in absolute terms the thinnest hand-wound watch ever created, trumping even the unreliable but awesomely thin Jean Lassale 1200 of 1976 that was just over 3mm (with a movement 1200 micrometers, or 1.2mm, thick).

In fact, the Altiplano Ultimate Concept comes just a month after Piaget’s claim to the title of the world’s thinnest automatic watch with the Altiplano Ultimate Automatic 910P, which now seems like a towering 4.3mm high.

Albeit still an experimental timepiece, the Altiplano Ultimate Concept is a barely-there 2mm high in its entirety, case, movement, crystal – everything. Make no mistake; the entire concept watch is the very same thickness as the thinnest movement in the world back in 1957, the landmark Piaget cal. 9P – Swiss watchmakers took several decades to travel a few millimetres downwards.

The brilliant but unlamented Jean Lassale cal. 1200. Image Jjcasalo/Wikipedia

Four years in development, the Altiplano Ultimate Concept is essentially a souped up (or rather, down) version of the Altiplano 900P launched in 2013, relying on several similar principles in the movement construction, while pushing the envelope on some clever new features.

One of the crucial factors in the slimness of the 900P was the case back doubling up as the main plate of the movement, meaning that many of the moving parts were mounted on the case back, resulting in a total height of 3.65mm, the slimmest on the market then. Notably the case-back-as-the-main-plate concept is actually an old one, having been pioneered in quartz movements by ETA in the 1970s, debuting in the Concord Delirium in 1979. ETA later recycled the concept for Swatch watches, as well as the super-slim Swatch Skin.

Naturally the Altiplano Ultimate Concept is built on the same foundation, with a wafer-thin case back serving as the movement’s base plate, but going even further and replacing the bridges as well. A consequence of that construction is the use of ballbearings instead of jewels, which is why the movement has just 13 jewels instead of the 21 in most good watches.

The case and base plate as one. Image Piaget

Like Piaget’s other recent record-setting thin watches, the Altiplano Ultimate Concept has its hands and dial are slightly recessed, sitting just below the narrow bridge. This protects the hands from touching the crystal and stopping the watch, which can happen when the watch is worn too tightly and the case bends ever so slightly.

A good portion of the slimming down was helped by making necessary components as flat as possible, while getting rid of parts that are not vital. As Piaget did with its recent ultra-thin movements, certain wheels of the movement were flattened from the traditional 0.2mm to a mere 0.12mm, which isn’t much thicker than a human hair.

The mainspring was stripped of its cover and drum, for instance, leaving just the ratchet wheel on top and ball bearings below. It’s worth pointing out that despite its razor-thin height, the mainspring is large enough to deliver a respectable 44-hour power reserve.

The rest of the way to 2mm was thanks to some out of the box thinking, for the concept watch boasts five additional patented innovations that further whittled down the height of the watch.

First of all, the slenderness of the 41mm case requires substantial rigidity, which is why it was constructed using a specific cobalt-based alloy – crucial since the watch case literally holds the gears and pivots of the movement, and the slightest distortion may impede function.

Altiplano Ultimate Concept at 2mm (above), and the chunky 4.3mm automatic below

The 2mm case calls for a barely-there sapphire crystal that’s an unbelievable 0.2mm, which is one fifth that of a standard watch. Amazingly, it still adheres to a modern water resistance rating of 30m. And that leads to the second patent: a groove along the rim of the case to accommodate both the crystal and the exact amount of adhesive required to keep it in place.

Another patent concerns the flat, rectangular “telescopic” crown that is seamlessly recessed into the caseband and secured to the winding stem with a “spring clip”. This miniaturised crown serves to protect the stem from impact since the crown sits flush with the case. But the downside of the mini-crown is the impossibility of operating it with bare fingers, which is why a tiny electronic drill-like tool is required for both winding and setting.

Also patented is the drastically reduced keyless works. Instead of a conventional winding pinion that rotates perpendicular to the movement, the  Altiplano Ultimate Concept relies on a patented worm gear system that consists of a small screw-like “worm” that directly meshes with a toothed gear (or the worm wheel), reducing the volume occupied as well as play between the wheels.

The mechanism for selecting the function of the crown (namely winding or setting) has been reduced to a lever fitted to an “intermediate wheel”, which engages with the respective gears for each function when the crown is pulled.

But the primary development responsible for its thinness is the patented construction of the balance wheel. To start with, the layout has been inverted, leaving the balance sitting above the hairspring. Visible at nine o’clock, the balance is “floating”, having neither a cock nor shock protection. Instead, the balance staff turns on ball bearings integrated within the base of the staff. And the rate is adjusted via a mobile stud since there’s no index regulator.

Visually the watch is striking, looking less mechanical than machine. The main plate is black coated, leaving all the movement parts standing in stark contrast. On the wrist it resembles a paper printout, which is a statement in itself.

Reducing the height of the watch also leads to severe weight loss: the watch tips the scales at just 21.7g – the equivalent of five sheets of A4 paper, or a Richard Mille Rafael Nadal wristwatch for the very rich.

Even the most prosaic component of the watch had to be reworked to accommodate its thinness. The alligator leather strap – seamless and glued, not stitched – measures a gossamer 1.1mm thick with a sliver of Kevlar running down its middle to prevent it from tearing.

Given the impracticality of its predominant quality, the Altiplano Ultimate Concept (ref. G0A43900) remains just that, a concept. However, expect to see a version tweaked to survive public consumption in the not too distant future, as well as some of the innovations propagating into other extra-thin watches.