Crafted in solid 18K pink gold (Au750), the Audemars Piguet Royal Oak Double Balance Wheel Openworked Ref. 15407OR.OO.1220OR.01 (198.5g) and the 41mm Selfwinding Flyback Chronograph Ref. 26240OR.OO.1320OR.01 (226.4g) represent the pinnacle of Le Brassus octagonal case geometry, hand-polished anglage, and integrated bracelet finishing.
Key Quantitative Laboratory Takeaways
- The Royal Oak Ref. 15407OR measures 41.0 mm by 9.9 mm and weighs 198.5 grams in solid 18K pink gold, showcasing slate-grey openworked bridges contrasted against a pink gold inner bezel and golden balance assembly.
- The 50th-Anniversary Royal Oak Chronograph Ref. 26240OR houses the integrated Flyback Calibre 4401 and weighs 226.4 grams on a full solid 18K pink gold bracelet.
- Eight hexagonal screws crafted in solid 18K white gold pass through the octagonal bezel and lock into threaded caseback nuts, aligning their slots in a perfect tangential circle.
- Over 140 individual flat links and connecting studs in the Royal Oak bracelet are hand-finished with alternating vertical satin brushing and mirror-polished chamfers.
| Reference Number | Model & Complication | Case & Bracelet Material | Case Thickness | Verified Mass (g) | Movement Calibre |
|---|---|---|---|---|---|
| Ref. 15407OR.OO.1220OR.01 | Royal Oak Double Balance Openworked | Solid 18K Pink Gold (Au750) | 9.9 mm | 198.5g | Cal. 3132 Openworked |
| Ref. 15407BC.GG.1224BC.01 | Royal Oak Frosted White Gold Openworked | Hammered 18K White Gold + Rainbow | 9.9 mm | 202.8g | Cal. 3132 Openworked |
| Ref. 26240OR.OO.1320OR.01 | Royal Oak 41mm Flyback Chronograph | Solid 18K Pink Gold (Au750) | 12.4 mm | 226.4g | Cal. 4401 Flyback |
| Ref. 15500OR / 15510OR | Royal Oak 41mm Selfwinding Date | Solid 18K Pink Gold (Au750) | 10.5 mm | 208.4g | Cal. 4302 Automatic |
| Ref. 16202OR / 15202OR | Royal Oak "Jumbo" Extra-Thin 39mm | Solid 18K Pink Gold (Au750) | 8.1 mm | 174.6g | Cal. 7121 / 2121 |
| Ref. 26579CE / 26585CE | Royal Oak Perpetual Calendar Openworked | Black Ceramic + 18K Rose Gold Accents | 9.9 mm | 114.2g | Cal. 5134 / 5135 |
How Does the Double Balance Wheel Architecture Work in Ref. 15407OR?
First patented by Audemars Piguet in 2016, the Double Balance Wheel mechanism in the Royal Oak Openworked Ref. 15407OR mounts two balance wheels and two hairsprings coaxially on the same axis, oscillating in perfect synchrony at 21,600 vph (3 Hz). By doubling the regulating organ's moment of inertia and placing the two hairsprings in opposition, positional gravity errors cancel out automatically, boosting chronometric stability by over 30% compared to a single-balance skeleton movement.
Framed by a ruthenium-toned slate-grey openworked mainplate and solid 18K pink gold applied hour markers, the golden balance bridge at 7 o'clock is visible from both the dial and sapphire caseback sides.
Why the Integrated Solid 18K Gold Royal Oak Bracelet Is a Masterpiece of Anglage
More than any other luxury sports watch, the Audemars Piguet Royal Oak derives its visual drama from the interplay of light across its integrated tapering bracelet. On a solid 18K pink gold Ref. 15407OR (198.5g) or Ref. 26240OR (226.4g), every horizontal link and twin connecting stud is CNC-milled from forged Au750 bar stock, vertically satin-brushed on its broad flat surfaces, and diamond-beveled along its top, bottom, and interior link edges.
As the wearer rotates their wrist, light cascades continuously from the eight-sided bezel chamfer down the uninterrupted beveled edge of the bracelet links—a hallmark of Geneva and Le Brassus hand-finishing that instantly separates our Private Vault builds from mass-market castings.
| Technical Attribute | Calibre 3132 (Ref. 15407OR) | Calibre 4401 (Ref. 26240OR) | Calibre 4302 (Ref. 15510OR) |
|---|---|---|---|
| Escapement & Balance | Coaxial Double Balance + Twin Hairsprings | Free-Sprung Variable Inertia Balance | Free-Sprung Gyromax Balance |
| Oscillation Frequency | 21,600 vph (3 Hz) High-Inertia | 28,800 vph (4 Hz) High-Beat Chrono | 28,800 vph (4 Hz) |
| Chronograph Mechanism | Time-Only Openworked Architecture | Integrated Column Wheel + Vertical Clutch | Center Seconds + Instant Jump Date |
| Winding Rotor Material | 22K Pink Gold Openworked Monobloc Rotor | 22K Pink Gold Skeletonized Rotor | 22K Pink Gold Openworked Rotor |
| Power Reserve | 45 – 50 Hours | 70 Hours | 70 Hours |
Inside Calibre 4401 on the 226.4-Gram Royal Oak Flyback Chronograph 26240OR
Replacing the long-serving modular Calibre 2385, the in-house integrated Calibre 4401 inside the Royal Oak Chronograph Ref. 26240OR features a vertical clutch (preventing seconds-hand stutter upon activation), a six-column wheel visible through the sapphire exhibition caseback, and an instantaneous flyback mechanism that resets and restarts the chronograph with a single press of the 4 o'clock pusher.
Explore Verified Audemars Piguet Solid 18K Gold References in Our Register
Every timepiece referenced in this monograph is available for immediate allocation with pre-shipment 4K Mettler-Toledo gram weighing, Fischer XRF Au750 spectroscopy, and 6-position Witschi Chronoscope certification. Navigate directly to the 18K VIP Homepage Master Register, the Audemars Piguet Solid 18K Gold Collection Hub, or the Complete 774-Watch Catalogue:
Former Senior Horological Specialist (Geneva & Hong Kong Auctions), FGA Certified Gemologist.
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