Ulysse Nardin Skeleton X

Introduction

The Ulysse Nardin Skeleton X (ref. 3713-260-3/03) is a watch that dares to bare it all. In a category often reserved for showpieces that live in watch winders, this titanium skeleton defies expectations by being genuinely wearable. I spent a full week with it—commuting, working, dining out, and even a weekend hike—to see if its openworked architecture could survive real life without becoming a scratch-magnet or a readability nightmare.

At first glance, the Skeleton X is a visual assault of bridges, gears, and a floating mainspring barrel. But Ulysse Nardin has been skeletonizing movements since the 1990s, and the UN-371 caliber inside this 43mm case is a mature expression of that craft. The brand’s marine chronometer heritage lends a precision ethos that underpins the artistry. The result is a watch that feels both avant-garde and grounded—a rare combination in the skeleton world.

This review focuses on how the Skeleton X performs on the wrist: lug-to-lug fit, legibility in varied lighting, strap comfort, and whether the openworked dial is a daily-driver or a weekend indulgence. Let’s cut through the glass and get to the wear.

Manufacture History

Ulysse Nardin was founded in 1846 in Le Locle, Switzerland, and built its reputation on marine chronometers for naval fleets. The brand’s precision timekeeping earned it contracts with over 50 navies worldwide. In the modern era, Ulysse Nardin reinvented itself as a pioneer of avant-garde watchmaking, introducing the Freak in 2001 and later embracing silicon technology. The Skeleton X line, launched in 2019, represents a fusion of this heritage with contemporary skeletonization, offering a wearable art piece that honors the brand’s chronometer roots while pushing design boundaries.

Movement

At the heart of the Skeleton X is the in-house UN-371 automatic movement. This caliber is a development of the UN-370, with extensive skeletonization that removes material from the bridges and mainplate to reveal the gear train. The movement operates at 28,800 vph (4 Hz) and boasts a 96-hour power reserve, thanks to a large mainspring barrel that is prominently displayed at 12 o’clock. The silicium hairspring and anchor provide antimagnetic properties, ensuring accuracy in daily wear. The openworked rotor, shaped like a stylized anchor, winds efficiently while offering an unobstructed view of the movement. Finishing is excellent: perlage on the mainplate, Côtes de Genève on the bridges, and beveled edges throughout. The movement is not COSC-certified, but in practice it performs well within chronometer standards.

Specifications

• Case Diameter: 43mm
• Case Thickness: 12.5mm
• Lug-to-Lug: 50mm
• Case Material: Titanium (black DLC coating on this reference)
• Crystal: Sapphire with anti-reflective coating
• Water Resistance: 50 meters (5 ATM)
• Lume: Super-LumiNova on hands and hour markers
• Bracelet/Strap: Black rubber strap with titanium pin buckle
• Clasp: Pin buckle

Wrist Feel

The Skeleton X wears surprisingly light for a 43mm watch. The titanium case keeps the weight down to around 85 grams on the rubber strap, and the 50mm lug-to-lug ensures it sits flat on my 6.75-inch wrist without overhang. The rubber strap is supple and curved, hugging the wrist without pinching. The pin buckle is titanium too, so no metal fatigue at the clasp point. I wore it for 12-hour days without needing to adjust—a rare comfort level for a skeleton watch, which often feels top-heavy due to openworked cases.

The balance is excellent: the movement is centrally mounted, and the openworked rotor doesn’t create a wobble. The crown is signed and easy to grip, though it’s not screw-down (50m WR means push-pull). The only minor gripe is the strap’s lack of quick-release spring bars—you’ll need a tool to swap straps. But the rubber is so comfortable that I never felt the urge to change it. Overall, the Skeleton X feels like a well-engineered daily tool, not a fragile art piece.

Accuracy

Over a week of mixed wear (office, gym bag, desk diving), the UN-371 ran consistently at +3 to +5 seconds per day. That’s excellent for a non-COSC movement, and the silicium escapement keeps it stable against magnetism. I’d trust it for daily use without second-guessing the time. The 96-hour power reserve is a real bonus—set it down Friday night, pick it up Monday morning, and it’s still running. No need for a winder.

Occasions

The Skeleton X is versatile enough for daily wear, dress occasions, and even formal events. The black DLC titanium and rubber strap keep it sporty, but the skeleton dial adds a level of sophistication that works under a cuff. I wouldn’t recommend it for swimming or high-impact sports due to the 50m water resistance, but it handles hand-washing and rain without issue. It’s a great travel companion—light, comfortable, and a conversation starter at dinner.

Wrist Presence

4/5 — The Skeleton X commands attention without being obnoxious. The openworked dial is a conversation starter, but the titanium case and black rubber strap keep it from screaming 'look at me.' It’s a watch that watch enthusiasts will notice, but civilians might just see a cool, modern timepiece. The lume is decent—hands and indices glow for a few hours—but legibility in bright sunlight is excellent thanks to the high contrast of the black bridges against the open spaces.

Reference Variants

The Skeleton X family includes several dial and strap options: the 3713-260-3/01 with blue PVD bridges and blue rubber strap, the 3713-260-3/02 with white bridges and white rubber strap, and the 3713-260-3/04 with rose gold PVD case and brown leather strap. The black DLC version reviewed here (3713-260-3/03) is the most stealthy and versatile.

Family and Other Models

Other notable Ulysse Nardin models include the Freak X (a more radical carousel watch), the Marine Torpilleur (a classic dress watch), the Diver Net (a sustainable dive watch), and the Blast (a skeletonized chronograph). The Skeleton X sits as the purest expression of skeletonization in the current lineup.

Similar Watches

If you’re considering the Skeleton X, you might also look at the Hublot Big Bang Unico Skeleton (heavier, more aggressive), the Zenith Defy Skeleton (lighter, more industrial), or the Roger Dubuis Excalibur Skeleton (more extravagant, less daily-wearable). Each offers a different take on the skeleton aesthetic.

Homages

For a budget-friendly alternative, the Invicta Pro Diver Skeleton (around $150) offers a similar openworked dial but with a quartz movement and much lower finishing quality. It’s a fun beater but no substitute for the Ulysse Nardin’s craftsmanship.

Investment Value

The Skeleton X retails for $13,500 and pre-owned examples typically range from $9,000 to $12,000. The market is stable, with no significant appreciation expected. It’s a niche piece that holds value reasonably well but is best purchased for the love of the design rather than as an investment. Auction history is minimal.

Service Interval

Ulysse Nardin recommends service every 5 years, costing approximately $800. Due to the specialized skeleton movement and silicium components, service must be performed by an authorized center. The 96-hour power reserve means you can rotate it with other watches without constant winding.

Pros and Cons

Pros

• Stunning skeletonization with excellent finishing
• Lightweight titanium case and comfortable rubber strap
• 96-hour power reserve with silicium escapement
• Good real-world accuracy (+3-5 spd)

Cons

• 50m water resistance limits swimming and showering
• Legibility can be tricky in very low light due to open dial
• No quick-release strap system
• Pricey for a time-only watch

Final Verdict

The Ulysse Nardin Skeleton X is a masterclass in skeleton watch design, offering a perfect balance of artistry and wearability. It's a daily-wearable piece of horological art that will turn heads without screaming for attention. If you want a skeleton watch you can actually live with, this is it.