Royal Tunku Ismail Ibni Sultan Ibrahim spotted wearing a Artisans De Genève

Spotted at what appears to be a casual golf outing, Tunku Ismail Ibni Sultan Ibrahim — Crown Prince of Johor and son of the current Yang di-Pertuan Agong of Malaysia — is wearing one of the rarest and most technically complex Rolex-based custom watches in existence: the Artisans De Genève Montoya Platinum Challenge. The sighting underlines the Crown Prince's well-documented appetite for serious horology, sitting comfortably alongside previous spots of grand complications and sports watches on his wrist.

Artisans De Genève, the Geneva-based atelier founded by Florian Serex, has built a global reputation for one specific discipline: the skeletonisation and personalisation of Rolex movements — work that Rolex itself does not officially sanction. The Montoya Platinum Challenge is the third personalisation created in collaboration with Colombian-American Formula 1 and IndyCar champion Juan Pablo Montoya. It takes a Rolex Daytona — based on the reference 116500LN platform — and strips the Cal. 4130 automatic chronograph movement down to its structural skeleton, then rebuilds it with platinum-treated bridges, sandblasted finishing on the movement components, and a translucent 'blue sky' dial that turns the entire watch into a horological display case.

The Cal. 4130, Rolex's in-house column-wheel chronograph calibre introduced in 2000, is widely regarded as one of the most robust and elegantly engineered chronograph movements in series production. Skeletonising it without compromising its COSC-certified precision is a genuine feat of micro-engineering. Artisans De Genève removes material from bridges and plates with surgical precision, then applies their own finishing regime — a process that can take hundreds of hours per piece. The flame-blued hands, visible clearly in the detail shot, are produced by controlled heat oxidation, a traditional haute horlogerie technique that adds a layer of visual drama to the open dial.

The Daytona base used here features the black ceramic bezel with tachymetre scale, the 40mm Oystersteel case, and the integrated Oyster bracelet — all signature elements of the 116500LN. Combined with the Artisans De Genève transformation, the result is a watch that occupies a unique space: production-car reliability wrapped in coachbuilt bodywork.

On the grey market, a standard Rolex Daytona 116500LN already commands a significant premium over its retail price. An Artisans De Genève Montoya edition — particularly the Platinum Challenge, produced in extremely limited numbers — operates in an entirely different price tier. Collectors pursuing this specific reference should expect to negotiate directly through the atelier or through a very short list of authorised partners. For a Crown Prince with an established watch collection of this calibre, it is a logical and thoroughly considered acquisition.