Richard Mille private treaty lots combine tripartite curved tonneau cases—milled from solid 18K 5N red gold (Au750), synthetic monobloc corundum sapphire (1,800 HV hardness), or North Thin Ply Technology (NTPT) carbon—with grade-5 titanium skeletonized tourbillon and automatic calibres weighing between 68.5g and 164.0g.
Key Quantitative Laboratory Takeaways
- Machining a three-part curved tonneau case from solid synthetic sapphire crystal (Al2O3, Mohs 9 / 1,800 Vickers) requires over 1,000 hours of 5-axis ultrasonic diamond grinding and optical polishing.
- In solid 18K Red Gold configurations (such as RM 011, RM 055, and RM 35-02), the satin-brushed Au750 bezel and caseback are torqued to an NTPT carbon or titanium middle case via 20 spline screws.
- The RM 52-05 Pharrell Williams Tourbillon features a sculpted grade-5 titanium astronaut helmet bridge with hand-applied enamel and a solid 18K gold visor assembly.
- Every Richard Mille lot in the 18K VIP Vault is verified for exact spline-screw torque, Nitril O-ring seal compression, and 6-position Witschi escapement telemetry.
| Vault Reference | Case & Bezel Materials | Movement Architecture | Case Dimensions | Verified Mass (g) | Escapement Spec |
|---|---|---|---|---|---|
| RM 52-05 Pharrell Williams | Brown Cermet + Solid 18K Gold Helmet Accent | Manual-Wind Flying Tourbillon | 49.94 x 42.35 x 16.15 mm | 78.3g – 84.0g | 21,600 vph Free-Sprung |
| RM 56-02 / RM 56 Sapphire | Tripartite Monobloc Crystalline Sapphire | Cable-Suspended Skeleton Tourbillon | 50.50 x 42.70 x 16.75 mm | 68.5g – 74.2g | 21,600 vph Titanium |
| RM 055 Bubba Watson Gold | Solid 18K Red Gold + White ATZ Ceramic | Cal. RMUL2 Skeletonized Manual | 49.90 x 42.70 x 13.05 mm | 142.6g | 28,800 vph Double Barrel |
| RM 35-02 Rafael Nadal 18K | Solid 18K Rose Gold + NTPT Carbon Midcase | Cal. RMAL1 Automatic Variable Rotor | 49.94 x 44.50 x 13.05 mm | 156.8g | 28,800 vph Grade-5 Ti |
| RM 67-02 / RM 67-01 18K | Solid 18K Rose Gold Ultra-Flat Tonneau | Cal. CRMA6 / CRMA7 Extra-Flat | 47.52 x 38.70 x 7.75 mm | 118.4g | 28,800 vph Pt/Au Rotor |
How Are Tripartite Curved Tonneau Cases Milled in Solid 18K Gold and Sapphire?
Unlike flat circular watch cases that can be turned on a conventional lathe, a Richard Mille tripartite tonneau case exhibits compound three-dimensional curvature across the bezel, middle caseband, and caseback simultaneously. To prevent any gap where dust or moisture could enter, the upper bezel and lower caseback must mate against the middle caseband within a 0.001 mm (1-micron) surface-flatness tolerance, clamped together by 20 grade-5 titanium spline screws and Nitril O-ring seals.
In our solid 18K Red Gold and Gold-Carbon NTPT vault lots, the bezel and caseback are milled from solid Au750 billets, given vertical satin brushing across the top arc, and finished with wide hand-polished bevels along the scalloped flanks.
Inside Grade-5 Titanium Skeleton Bridges and Free-Sprung Tourbillons
At the heart of our Richard Mille private treaty allocations—from the RM 52-05 Tourbillon to the skeletonized RM 055 and RM 35-02—is a baseplate and bridge architecture machined from biocompatible Grade-5 Titanium (90% titanium, 6% aluminum, 4% vanadium) treated with black or grey electroplasma oxidation. This rigid, low-mass chassis supports fast-rotating twin mainspring barrels and a free-sprung variable-inertia balance wheel operating at 21,600 vph (on tourbillon calibres) or 28,800 vph (on RMUL2 and RMAL1 calibres), delivering shock resistance tested to over 5,000 Gs.
| Case Material | Vickers Hardness (HV) | Density (g/cm3) | 5-Axis Milling Cycle | Optical / Tactile Signature |
|---|---|---|---|---|
| Solid 18K 5N Red Gold (Au750) | 190 HV (Forged) | 15.25 g/cm3 | 42 Hours + Hand Anglage | Deep Warm Rose Lustre & High Wrist Mass |
| Monobloc Crystalline Sapphire | 1,800 HV (Scratch-Proof) | 3.98 g/cm3 | 430 – 1,000 Hours Ultrasonic | 99.4% Optical Transparency (360-Deg View) |
| NTPT Carbon / Gold Leaf Quartz | 1,150 HV Composite | 1.78 g/cm3 | 35 Hours 45-Deg Ply Milling | Damascus Wave Striations + 24K Gold Foil |
| Grade 5 Titanium (Ti-6Al-4V) | 349 HV (PVD Treated) | 4.43 g/cm3 | 28 Hours Micro-EDM | Micro-Blasted Matte Grey Movement Bridges |
Verifying Authentic Mass and Alloy Purity on Hybrid Gold-Carbon RM Lots
When a collector reserves a hybrid solid 18K Red Gold and NTPT Carbon Richard Mille lot through 18K VIP Geneva, our laboratory records a dual verification dossier: Fischer XRF spectroscopy directly on the solid 18K gold bezel, caseback, and deployant clasp wing confirming 75.0% Au750 fineness, alongside a Mettler-Toledo total weight measurement (142.6g to 156.8g on gold-cased models, or 68.5g to 78.3g on pure sapphire and cermet tourbillons).
Explore Verified Richard Mille 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 Richard Mille 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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