Tough and Transparent: Richard Mille Tourbillon RM 56-02 Sapphire Written byMark BernardoFebruary 18, 2015 Richard Mille pioneered the use of an all-sapphire watch case with its RM 056 Sapphire Tourbillon Split Seconds Chronograph in 2011, and upped the technological ante with the subsequent debut of the RM 56-01, which also had baseplates, bridges and a third wheel made of sapphire. Last year saw the debut of another innovation, the Richard Mille Tourbillon RM 56-02 Sapphire, which combines a tripartite sapphire case with the brand’s revolutionary “cabled movement” design. The movement architecture used in the Richard Mille Tourbillon RM 56-02 Sapphire takes its cues from the movement in another Richard Mille watch, the RM 27-01 Rafael Nadal, developed with the input of the Spanish tennis star. The baseplate of the RM 56-02 movement is made of tough but lightweight titanium and suspended within the all-sapphire case by means of a single-braided cable only .35 mm thick. The movement uses a system of four pulleys on posts at its corners and another six pulleys along its periphery; a miniature ratchet at 9 o’clock controls the tension of the cables. The entire system mis connected to an indicator at 12 o’clock that enables the wearer to check the tension in the pulleys to make sure its operating within the designated norms. The transparent sapphire case — which is made up of three parts, each milled and ground from blocks of solid sapphire — has a hardness of 1,800 Vickers and is virtually scratch-resistant to any material short of diamond. Sapphire is also used in movement parts, including the winding barrel bridge, the center bridges, and even the tourbillon. Every RM 56-02 watch, created by the specialists at the Stettler firm in Lysa, Switzerland, requires 40 days of continuous 24/7 machining for the case followed by 400 additional hours for machining and finishing of the movement bridges. Despite its somewhat delicate look, the Richard Mille Tourbillon RM 56-02 Sapphire is water-resistant to 3o meters thanks to two transparent nitrile O-rings assembled with 24 spline screws made of grade 5 titanium. Both the front and back bezels of the case are treated with anti-glare protection. The “see-through” aesthetic extends to the partially translucent strap, created exclusively for Richard Mille from a proprietary Aerospace Nano material whose silky, organic texture complements the ergonomic design of the case. The Richard Mille Tourbillon RM 56-02 Sapphire is an extraordinarily limited edition, priced for a very fortunate few; only 10 pieces will be available worldwide, priced at $2,020,000. (Click on the photos for larger images.) This article was originally published on July 13, 2014, and has been updated.