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RM 75-01 Flying Tourbillon Sapphire: Richard Mille is crystal clear

The three versions of the RM 75-01 Flying Tourbillon Sapphire
The three variants of the RM 75-01 Flying Tourbillon Sapphire are shown here. From left to right are the versions with: - a transparent sapphire bezel and case, and a blue sapphire back (limited to 10 pieces); - a completely transparent sapphire case (limited to 15 pieces); - a transparent sapphire bezel and case, and a pink-lilac sapphire back (limited to 10 pieces).
The RM 75-01 Flying Tourbillon Sapphire, viewed from below
This is the backside of the RM 75-01 Flying Tourbillon Sapphire. Creating coloured sapphire crystals requires the precise incorporation of metal oxides. The colour of the crystal is determined by the types and quantities of oxides present. Coloured sapphire is highly sensitive to heating and crystal growth rates; if the correct temperature conditions are not met, the diffusion of the oxides in the crystal lattice can be affected, leading to uneven colour distribution or undesirable shades. This is why the production process is so complex.
The RM 75-01 case
The case measures 32.9 x 46.75 x 14.35 mm. Its tonneau shape and tripartite construction, comprising the back, middle section and bezel, are typical of Richard Mille, as are the 'pillars' inside the middle section that accommodate the passing screws. Despite its unusual material composition, the case is water resistant up to 3 bar thanks to two nitrile O-rings.
A different perspective on the RM75-01 case.
The lilac sapphire crystal on the back of the case gives it a pink hue, which is accentuated by the 5N red gold details. Thanks to this structure, the human eye perceives colour where there is actually only transparency. The distinctive 5N red gold crown comprises several overlapping elements, including a rubber gasket and a row of brilliant-cut diamonds. Mounting these small gems on the griffes must have been a nightmare for the setter, but they undoubtedly create additional reflections.
The structure of the case of the RM 75-01 Flying Tourbillon Sapphire.
The sapphire machining process is extremely delicate. Although the material is extremely robust, it does not forgive the slightest error during milling and cutting. Creating a case of this quality requires over 1,000 hours of work, with 430 hours dedicated to pre-forming the components and 350 hours to polishing. To ensure optimal optical properties, an anti-reflective coating is applied to the front and back bezels.
Special grade 5 titanium screws
Richard Mille uses grade 5 titanium slotted head screws for the bridges and case. Thanks to the design of the screw head, greater control can be exerted over the torque applied when assembling the various parts. They are also resistant to wear and tear during maintenance operations, thus making the work of watchmakers easier, and they age very well, ensuring a long tightening duration.
The RM 75-01 seen from below
The beautiful structure of the RM75-01 calibre is visible through the tinted sapphire crystal case back. The rose gold colour of the components accentuates their visibility. The skeleton plate and bridges have undergone rigorous testing to ensure they meet stringent resistance requirements. This hand-wound mechanical movement operates at 21,600 vibrations per hour and boasts a 65-hour power reserve.
A close-up of the RM 72-01 dial
The dial details reveal a balanced layout, with the barrel positioned symmetrically in relation to the tourbillon. This fast-rotating flying barrel completes a full revolution in just 5.2 hours, providing several benefits. It minimises the spring's occasional adherence to the internal surfaces and provides an excellent 'delta' to the spring force release curve. This ensures an ideal balance between autonomy and rate constancy, optimising performance.
The plate and bridges of the RM 75-01 calibre
The plate and bridges of the RM75-01 calibre are made of Grade 5 titanium and feature a red gold and grey PVD surface treatment. Grade 5 titanium is a highly corrosion-resistant, stiff alloy that is biocompatible and allows the gear train to function properly. Composed of 90% titanium, 6% aluminium and 4% vanadium, it is a combination that provides titanium with optimal mechanical properties, making it ideal for use in the aerospace, aviation and automotive industries.
Assembling the RM 75-01 calibre
The flying tourbillon, positioned at the 6 o'clock position, is a highly intricate regulator. As connoisseurs will know, the term 'flying' refers to the way the cage is assembled without an upper bridge for support. This creates the impression that the tourbillon is floating, making it fully visible. The free-sprung, variable-inertia balance guarantees greater reliability in the event of shocks during assembly and disassembly, as well as more accurate timekeeping over time.
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This post is also available in: Italian

If the great 17th century French philosopher and writer François de La Rochefoucauld were alive today, he might well be wearing a Richard Mille watch. Perhaps the RM 75-01 Flying Tourbillon Sapphire, the brand’s latest model. After all, as he wrote in one of his most famous aphorisms, ‘The only thing that should surprise us is that there are still some things that can surprise us’. This is precisely how I felt when I saw the initial images of this new watch − unfortunately, only those for now. I was astonished.

Above all, I was astonished by the brand’s ability to continually master the most advanced materials in watch manufacturing: Quartz TPT, carbon TPT, ceramic, gold, titanium and, of course, sapphire. Richard Mille’s ability to shape these materials, ranging from ‘simple’ to composite, establishes the brand as one of the most advanced in this field. The RM 75-01 Flying Tourbillon Sapphire is further proof of this, particularly for those familiar with working with sapphire.

Lords of Sapphire

Essentially, it involves operating on the edge of masochism. The sapphire used for watch cases, like the RM 75-01 Flying Tourbillon Sapphire, is a synthetic material produced in a laboratory. Technically, it is synthetic corundum, which is notable not so much for its transparency as for its hardness, which is surpassed only by that of a diamond.

This article explains the process of machining such a hard and resistant material. Over 10 years ago, Richard Mille became the first brand to use this material for watch cases. That was in 2012, which feels like a geological era ago. Consider what has happened to the watch market in the meantime, from the pandemic to the explosion and subsequent implosion in China − just two key episodes.

The RM 75-01 Flying Tourbillon Sapphire continues this legacy and takes excellence even further. The 2012 watch combined two of the most highly regarded complications: a split-seconds chronograph and a tourbillon. This model “limits” itself to a flying tourbillon. However, materials science and calibre technology have evolved at an incredible speed in the intervening 13 years. Richard Mille has kept pace, needless to say.

The colours of the RM 75-01 Flying Tourbillon Sapphire

With that in mind, let me introduce today’s watch. There are actually three versions, as the brand has worked with three different colours of sapphire. More specifically, the sapphire back is available in three versions: completely transparent, blue and lilac-pink. There are several possible reasons for limiting the colour to the case back.

Undoubtedly, creating a fully coloured sapphire case is complex. Minerals must be added to the basic corundum to give the material the desired colour: titanium and iron for blue, for example. Needless to say, achieving the desired shade by finding the right proportion of additives is not easy. Richard Mille certainly does not compromise on quality. However, if a ‘cheap’ solution can be found in terms of cost and processing time, why not use it?

Another possible reason is ‘scenographic’: an entirely coloured sapphire case could distract from the calibre, the real protagonist of the watch’s design. However, more prosaically, I believe that the choice of a coloured case back was made because, despite being only part of the watch and located at the rear, its transparency captures nuances and virtually colours it as well.

This would be an intelligent way to achieve a high-quality result while reducing the effort involved in the challenging production of coloured sapphire. It is no coincidence that only 15 pieces of the fully transparent version are manufactured, while the blue and lilac pink versions are limited to 10 due to obvious production difficulties.

The RM75-01 calibre finish

I will now move on to the movement. This is the hand-wound RM75-01 calibre, featuring a flying tourbillon and an hour and minute display. There are no additional complications, counters or function selectors. It would appear minimalist were it not a Richard Mille. While I will leave most of the technical details to the captions, it is worth emphasising here that the movement is distinguished not only by its mechanical complexity, but also by its very high level of refinement.

The chamfers, locking elements and contact surfaces are hand-polished, as are the pivots. To achieve the micro-peened effect of the milling, Richard Mille used sapphire microspheres. The steel parts have also been sandblasted using sapphire microspheres (the mainplate and bridges are made of titanium) and have polished sides.

As with all the brand’s movements, great care was taken when manufacturing the geared wheels of the RM75-01 calibre. Their concave bevels were made using custom-made diamond tools to achieve micron-level precision. The faces of the wheels have a circular satin finish and are rhodium-plated before the gearing is made, to eliminate any defects or imperfections. The wheels undergo minimal corrections; any alteration to their geometry would compromise the performance of the time train.

Richard Mille DNA

In the press kit for the RM 75-01 Flying Tourbillon Sapphire, the brand describes the watch as “…embodying a metaphysical balance. The modernity and technical sophistication of its sculptural calibre harmonise with a timeless inspiration drawn from historical architecture and the softness of the oceans — a duality that perfectly reflects the brand’s artistic and technical approach, where diverse worlds converge to open new creative horizons“.

I will grant the authors some poetic licence. After all, marketing is neither about technique nor passion. In this sense, the focus on colour nuances inspired by the shades of the sea is fitting. However, we must not forget that this is primarily a mechanical watch, an achievement made all the more impressive by the fact that it combines a complex architectural structure with the basic function of displaying the hours and minutes, enhanced by the flying tourbillon.

Given the commitment to materials, technology, research and development that the Manufacture has invested in the watch, the price tag of around 2 million Swiss francs is entirely predictable. As I mentioned at the beginning, this is something one should no longer be surprised by. Richard Mille embodies innovation, mechanical avant-garde and materials science, as well as an obsession with research. All of this comes at a cost commensurate with the quality of the final product, and the RM 75-01 Flying Tourbillon Sapphire is no exception. Excellence and perfection have never been for everyone.