GEM-SET watches have often been judged by the beauty of their exterior, rather than the sophistication of their mechanics.
While dazzling diamonds and precious stones command immediate attention, often such timepieces house relatively simple movements, placing more emphasis on aesthetics instead of horological ambition.
Richard Mille has long challenged such conventions, and this is especially evident in the RM HJ-02 In-House Automatic Tourbillon.
Beneath its brilliant gem-set facade is an entirely new movement, the CRMT2 calibre, engineered to the exacting standards the brand is renowned for.
This skeletonised automatic-winding tourbillon was specially developed to accommodate the timepiece’s jewel-studded case and dial.
The integrated approach ensures that mechanics and aesthetics complement one another, allowing neither to compromise the other.
The CRMT2, measuring 23.7mm by 30.7mm with a thickness of 6.2mm, is built on a gem-set white gold baseplate and bridges that are microblasted, bevelled and rhodium-plated.
Instead of being concealed beneath decorative surfaces, the movement’s skeletonised construction exposes its essential components, allowing light to travel through the calibre while reducing unnecessary mass without sacrificing rigidity.
One of its defining features is the free-sprung balance with variable inertia.
Unlike conventional regulating systems that rely on an index to adjust timing, the CRMT2 eliminates the regulator entirely.
Precision is instead achieved through four adjustable setting weights mounted directly on the balance wheel.
This configuration delivers greater stability when subjected to shocks, while providing more precise and repeatable adjustment over its lifetime.
This also contributes to improved chronometric performance, particularly after servicing or repeated assembly and disassembly.
Beating at a frequency of 28,800 vibrations per hour (4 Hz), the variable-inertia tourbillon is the dynamic heart of the movement.
More than a visual spectacle, it exemplifies Richard Mille’s commitment to precision engineering, with every component designed for consistent performance and architectural integrity.
Power delivery received equally careful attention.
The CRMT2 is equipped with a fast-rotating barrel that completes one revolution every five hours instead of the conventional seven-and-a-half.
This significantly reduces the phenomenon of periodic internal mainspring adhesion, helping deliver more consistent torque throughout the power reserve.
The result is improved regularity while maintaining approximately 50 hours of autonomy.
Further contributing to the movement’s efficiency is Richard Mille’s specially developed gear tooth profile.
The entire going train employs a 20-degree pressure angle, a geometry designed to equalise minor discrepancies that can arise between wheel centres through thermal variation or prolonged use.
By ensuring smoother torque transmission to the balance wheel, the system supports both long-term reliability and stable chronometric performance.
Beauty in motion
Turning the watch over reveals another example of Richard Mille’s holistic design philosophy.
The automatic winding rotor is itself transformed into a decorative composition without sacrificing its mechanical function.
Crafted from gem-set gold and mounted on ceramic ball bearings, it incorporates the brand’s one-way reverser system to optimise winding efficiency.
Ornamental stones such as turquoise and malachite create saturated bands of colour across the rotor, while calibrated precious stones reinforce this visual dialogue.
Notably, this decorative treatment never obscures the movement’s purpose.
Every element remains fully functional, demonstrating the manufacture’s determination to integrate artistry into engineering rather than allowing one to overshadow the other.
The finishing applied to the CRMT2 further reflects these meticulous standards.
Hand-polished anglage and stepped bevelling highlight the edges of the white gold bridges, while micro-blasted surfaces and sinks create subtle textural contrasts.
Electroplasma treatment of the baseplate and PVD treatment of the bridges enhance durability while preserving the movement’s distinctive appearance.
Elsewhere, steel components receive satin-finished surfaces, polished sinks and burnished sections, while the wheels feature diamond-polished sinks, rhodium plating, and circular decorations.
Every finishing technique serves both aesthetic and functional purposes, maintaining the movement’s geometry while enhancing visual clarity.
Built to perform
Although conceived as a high jewellery creation, the RM HJ-02 remains unmistakably a Richard Mille at heart.
The CRMT2 calibre undergoes the same rigorous validation programme applied across the manufacture’s broader collection, including extensive shock and reliability testing.
Such procedures ensure that movement withstands the demands of everyday wear without compromising on long-term performance – a philosophy that is synonymous with the brand’s engineering-first approach.
That commitment extends to the watch’s exterior.
The tripartite white gold case is assembled using Grade 5 titanium spline screws and abrasion-resistant stainless steel washers, while twin nitrile O-ring seals provide water resistance up to 50m.
Sapphire crystals with anti-glare treatment on both the front and caseback allow unobstructed views of the inner workings from either side.
Ultimately, the RM HJ-02 demonstrates that high jewellery and high horology need not exist as separate disciplines.
The CRMT2 calibre was never conceived to be a movement hidden beneath an extravagant exterior, nor was the jewellery added merely to elevate a technical watch.
Instead, both were developed simultaneously as parts of a unified vision in which engineering, materials and craftsmanship exist in complete harmony.
The result is a timepiece which brilliance extends far beyond its 1,399 precious and ornamental stones.
With the RM HJ-02, technical innovation and artistic expression have become inseparable, proving that true luxury is measured not only by what catches the eye, but also by the remarkable engineering hidden in plain sight.
