Head-to-Head Comparison

Updated September 5, 2026

Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue) vs Zenith Chronomaster El Primero Open Power Reserve (18k rose gold)

Ulysse Nardin's timepiece meets Zenith's chronograph

Quick Verdict

The Zenith Chronomaster El Primero Open Power Reserve (18k rose gold) ($10,000–$25,000) delivers El Primero 4021, 36,000 vph (5 Hz), column wheel, automatic technology in the tier below the Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue) ($25,000+). The Chronomaster El Primero Open Power Reserve (18k rose gold) measures 42mm and is rated 100m (10 ATM). The Executive Skeleton X 42mm (18k rose gold, blue) justifies its premium with Swiss Made heritage and Hand-wound, Ulysse Nardin UN-371 (skeleton). Both represent excellent choices in the luxury watch category.

Ulysse NardinExecutive Skeleton X 42mm (18k rose gold, blue)$25,000+ Check price ZenithChronomaster El Primero Open Power Reserve (18k rose gold)$10,000–$25,000 Check price

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Ulysse Nardin

Executive Skeleton X 42mm (18k rose gold, blue)

$25,000+

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Zenith

Chronomaster El Primero Open Power Reserve (18k rose gold)

$10,000–$25,000

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Specifications Compared

Feature	Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue)	Zenith Chronomaster El Primero Open Power Reserve (18k rose gold)
Price	$25,000+	$10,000–$25,000
Case Size	42mm	42mm
Movement	Hand-wound, Ulysse Nardin UN-371 (skeleton)	Automatic chronograph, Zenith El Primero 4021
Caliber Type	UN-371, hand-wound, silicon escapement and balance spring	El Primero 4021, 36,000 vph (5 Hz), column wheel, automatic
Power Reserve	About 96 hours (four days)	About 50 hours, with indicator
Water Resistance	100m (10 ATM)	100m (10 ATM)
Crystal	Sapphire Crystal, sapphire caseback	Sapphire Crystal, sapphire exhibition caseback
Case Material	18k rose gold, blue bezel	18k rose gold
Origin	Swiss Made	Swiss Made

Category-by-Category Analysis

🎨

Design & Aesthetics

Edge: Draw

Ulysse Nardin's design language vs Zenith's approach

The Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue) features a 18k rose gold, blue bezel case at 42mm with Sapphire Crystal, sapphire caseback protection. The Zenith Chronomaster El Primero Open Power Reserve (18k rose gold) offers 18k rose gold construction at 42mm with Sapphire Crystal, sapphire exhibition caseback. Both represent their brand's distinct design philosophy and heritage.

⚙️

Movement & Performance

Edge: Ulysse Nardin

Hand-wound, Ulysse Nardin UN-371 (skeleton) vs Automatic chronograph, Zenith El Primero 4021

The Executive Skeleton X 42mm (18k rose gold, blue) runs the Hand-wound, Ulysse Nardin UN-371 (skeleton) (UN-371, hand-wound, silicon escapement and balance spring, About 96 hours (four days) power reserve) at standard frequency. The Chronomaster El Primero Open Power Reserve (18k rose gold) uses the Automatic chronograph, Zenith El Primero 4021 (El Primero 4021, 36,000 vph (5 Hz), column wheel, automatic, About 50 hours, with indicator reserve) at standard. The Executive Skeleton X 42mm (18k rose gold, blue) edges ahead on power reserve.

📏

Wearability & Fit

Edge: Draw

42mm vs 42mm — different wrist presence

At 42mm, the Executive Skeleton X 42mm (18k rose gold, blue) is similarly sized compared to the Chronomaster El Primero Open Power Reserve (18k rose gold) at 42mm. Water resistance differs: 100m (10 ATM) vs 100m (10 ATM).

💰

Value & Cost of Ownership

Edge: Zenith

Zenith sits in the lower tier

The Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue) sits at $25,000+ and the Zenith Chronomaster El Primero Open Power Reserve (18k rose gold) at $10,000–$25,000. On the specs that outlast any price: the Executive Skeleton X 42mm (18k rose gold, blue) uses Sapphire Crystal, sapphire caseback with About 96 hours (four days), against Sapphire Crystal, sapphire exhibition caseback and About 50 hours, with indicator on the Chronomaster El Primero Open Power Reserve (18k rose gold). Service intervals are typically 5-7 years for both.

💧

Water Resistance

Edge: Draw

100m (10 ATM) vs 100m (10 ATM)

The Executive Skeleton X 42mm (18k rose gold, blue) is rated to 100m (10 ATM) while the Chronomaster El Primero Open Power Reserve (18k rose gold) handles 100m (10 ATM). Both offer identical water resistance ratings.

Our Verdict

Ulysse Nardin

Executive Skeleton X 42mm (18k rose gold, blue)

Choose the Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue) if you prioritize UN-371, hand-wound, silicon escapement and balance spring engineering, Swiss Made craftsmanship, and 100m (10 ATM) water resistance. At $25,000+, it delivers Hand-wound, Ulysse Nardin UN-371 (skeleton) with About 96 hours (four days) power reserve.

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Zenith

Chronomaster El Primero Open Power Reserve (18k rose gold)

Choose the Zenith Chronomaster El Primero Open Power Reserve (18k rose gold) if you value El Primero 4021, 36,000 vph (5 Hz), column wheel, automatic technology, Swiss Made heritage, and 42mm proportions. At $10,000–$25,000, the Automatic chronograph, Zenith El Primero 4021 with About 50 hours, with indicator power reserve makes it a compelling choice.

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The Bottom Line

The Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue) and Zenith Chronomaster El Primero Open Power Reserve (18k rose gold) represent two distinct approaches to fine watchmaking — the Ulysse Nardin bringing Swiss Made tradition while Zenith delivers Swiss Made engineering.

Frequently Asked Questions

On price, the Zenith Chronomaster El Primero Open Power Reserve (18k rose gold) sits a band lower ($10,000–$25,000 against $25,000+), so it is the cheaper way into the category. Neither is better at everything; the spec table above shows movement, case size, water resistance and crystal side by side so you can weigh what matters to you. We do not test units, so this is the makers' data, not a bench result.

The Zenith Chronomaster El Primero Open Power Reserve (18k rose gold) offers better upfront value, sitting a tier lower at $10,000–$25,000. However, the Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue) may justify its premium with superior finishing, heritage, or resale value.

Both are suitable for daily wear. The Executive Skeleton X 42mm (18k rose gold, blue) at 42mm with 100m (10 ATM) water resistance handles everyday situations. The Chronomaster El Primero Open Power Reserve (18k rose gold) at 42mm with 100m (10 ATM) is similarly capable. The Executive Skeleton X 42mm (18k rose gold, blue) uses Sapphire Crystal, sapphire caseback while the Chronomaster El Primero Open Power Reserve (18k rose gold) uses Sapphire Crystal, sapphire exhibition caseback.

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Ulysse Nardin Executive Skeleton X 42mm (18k rose gold, blue) — Full Review Zenith Chronomaster El Primero Open Power Reserve (18k rose gold) — Full Review Browse All Guides

How This Page Was Made

Our comparisons are generated from a hand-maintained specification database and reviewed under our editorial standards. We use AI tools to assemble pages from that data. We don’t invent specs: every number traces back to the database, and when we correct an entry, the fix is applied site-wide. As an Amazon Associate, The Horologist earns from qualifying purchases.