Snap up one of only three limited-edition, transparent timepieces – available exclusively on MR PORTER.

First launched in 2005, the square case of the Bell & Ross BR01 has become the brand’s instantly recognisable visual identifier. Modelled on cockpit instruments from small aircraft, it’s a signature that exemplifies the brand’s dedication to sturdy, utilitarian design, but also its willingness to step beyond the ordinary in its aesthetic choices. Even given all this, it was hard not to be impressed – a little startled, even – by the launch of the BR-X1 Chronograph Tourbillon Sapphire in 2016.

In this spectacular iteration of 2014’s BR-X1, a transparent sapphire case further revealed the intricate details of the brand’s skeletonised BR-CAL.283 movement, a hand-wound construction with a chronograph and flying tourbillon. Given that, to create each case, it was necessary to shape six blocks of sapphire (among the hardest materials on the planet) over hundreds of hours, this was issued in a limited edition of just five pieces worldwide. And then they were gone.

At this year’s Baselworld, however, Bell & Ross is taking the idea of transparency to new heights – and more importantly, issuing a few more spectacular watches – with the launch the BR-X1 Skeleton Tourbillon Sapphire. This new sapphire-cased BRX1, limited to three pieces worldwide, echoes the 2016 edition with its five-block sapphire case, but adds an exclusive new movement that, thanks to its stripped-back construction, offers an even more startling sense of lightness and transparency when worn on the wrist.

The hours and minutes are displayed on an off-centre, open-worked dial at 12 o’clock, which features Superluminova-filled hour and minutes hands. At six o’clock, a flying tourbillon appears to float, suspended in the middle of the case from the skeletonised bridge. It’s a watch that combines one of watchmaking’s oldest and most prestigious complications – the tourbillon – with a technically astonishing, thoroughly contemporary method of putting the mechanics proudly on display. In this sense, it feels somewhat audacious. But in a good way, of course.

“It’s a bit like an X-ray image,” says Ms Elsa Neri, the brand’s global communications director. “It lets us visualise the movement’s structure and understand its assembly by allowing the eyes to look at its heart.”

In each of the three BR-X1 Skeleton Tourbillon Sapphire watches that are being released today, a different, single colour – black, rose gold and royal blue – has been used for the main plate, bridges, dial, hands and tourbillon cage. This means that each piece is not only limited, but unique. What’s even more exciting is that the royal blue variation is, as of today, available to purchase online, exclusively at MR PORTER. Of course, at £355,000 ($480,000; €400,000), it’s not an everyday price tag. But, we think you’ll agree, this is not an everyday watch.