Longines Master Collection Moonphase vs Seiko Prospex "Turtle"
Longines's dress watch meets Seiko's diver
Quick Verdict
The Seiko Prospex "Turtle" ($500–$1,000) delivers In-House Automatic Manufacture technology in the tier below the Longines Master Collection Moonphase ($2,500–$5,000). The Prospex "Turtle" measures 45mm and is rated 200m (20 ATM) Diver. The Master Collection Moonphase justifies its premium with Swiss Made heritage and Automatic Caliber L899. Both represent excellent choices in the luxury watch category.
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Specifications Compared
| Feature | Longines Master Collection Moonphase | Seiko Prospex "Turtle" |
|---|---|---|
| Price | $2,500–$5,000 | $500–$1,000 |
| Case Size | 40mm | 45mm |
| Movement | Automatic Caliber L899 | Automatic Caliber 4R36 |
| Caliber Type | Automatic (ETA A31.L91 base) | In-House Automatic Manufacture |
| Power Reserve | 72 Hours | 41 Hours |
| Water Resistance | 30m (3 ATM) | 200m (20 ATM) Diver |
| Crystal | Sapphire Crystal | Sapphire Crystal |
| Case Material | Stainless Steel | Stainless Steel |
| Origin | Swiss Made | Made in Japan |
Category-by-Category Analysis
Design & Aesthetics
Longines's design language vs Seiko's approach
The Longines Master Collection Moonphase features a Stainless Steel case at 40mm with Sapphire Crystal protection. The Seiko Prospex "Turtle" offers Stainless Steel construction at 45mm with Sapphire Crystal. Both represent their brand's distinct design philosophy and heritage.
Movement & Performance
Automatic Caliber L899 vs Automatic Caliber 4R36
The Master Collection Moonphase runs the Automatic Caliber L899 (Automatic (ETA A31.L91 base), 72 Hours power reserve) at 25,200 vph (3.5 Hz) frequency. The Prospex "Turtle" uses the Automatic Caliber 4R36 (In-House Automatic Manufacture, 41 Hours reserve) at 21,600 vph (3 Hz). The Master Collection Moonphase edges ahead on power reserve.
Wearability & Fit
40mm vs 45mm — different wrist presence
At 40mm, the Master Collection Moonphase wears more compactly on smaller wrists compared to the Prospex "Turtle" at 45mm. Water resistance differs: 30m (3 ATM) vs 200m (20 ATM) Diver.
Value & Cost of Ownership
Seiko sits in the lower tier
The Longines Master Collection Moonphase sits at $2,500–$5,000 and the Seiko Prospex "Turtle" at $500–$1,000. On the specs that outlast any price: the Master Collection Moonphase uses Sapphire Crystal with 72 Hours, against Sapphire Crystal and 41 Hours on the Prospex "Turtle". Service intervals are typically 5-7 years for both.
Water Resistance
30m (3 ATM) vs 200m (20 ATM) Diver
The Master Collection Moonphase is rated to 30m (3 ATM) while the Prospex "Turtle" handles 200m (20 ATM) Diver. The Prospex "Turtle" offers superior water resistance.
Our Verdict
Longines
Master Collection Moonphase
Choose the Longines Master Collection Moonphase if you prioritize Automatic (ETA A31.L91 base) engineering, Swiss Made craftsmanship, and 30m (3 ATM) water resistance. At $2,500–$5,000, it delivers Automatic Caliber L899 with 72 Hours power reserve.
Check Price on AmazonSeiko
Prospex "Turtle"
Choose the Seiko Prospex "Turtle" if you value In-House Automatic Manufacture technology, Made in Japan heritage, and 45mm proportions. At $500–$1,000, the Automatic Caliber 4R36 with 41 Hours power reserve makes it a compelling choice.
Check Price on AmazonThe Bottom Line
The Longines Master Collection Moonphase and Seiko Prospex "Turtle" represent two distinct approaches to fine watchmaking — the Longines bringing Swiss Made tradition while Seiko delivers Made in Japan engineering.
Frequently Asked Questions
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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.