Introducing Bell & Ross’ new glow-in-the-dark BR 03-92 Diver Full Lum

The latest, square-cased dive watch from the French-Swiss horologist employs two-tone Super-LumiNova to full phosphorescent effect

Bell & Ross launches a luminous adventure watch alongside a blue-on-bronze tribute to the spirit of deep-sea diving

31 July 2020

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ave you ever wondered how it is that the hands and indices of your spring-loaded timepiece – that is to say a watch without the light-emitting capabilities of a battery – still glow in the dark several hours after they’ve been exposed to any sort of natural light? The answer is a material called Super-LumiNova. The story of Super-LumiNova, if you'll permit me a quick history lesson (if not, then skip to the bottom of this page for full specs of Bell & Ross' new BR 03-92 Diver Full Lum), begins with a man named Kenzo Nemoto.

Before World War Two, Kenzo Nemoto had been a newspaper reporter and the editor of a children’s science magazine. On 8 December 1941, a radio broadcast announced that Nemoto’s native Japan had declared war on the Allied forces. The news prompted the erstwhile journalist to swap his typewriter for another of his passions – painting, or, more specifically, the science of luminous dye.

Nemoto set up an eponymous paint manufacturing business and during the war was awarded contracts to equip Japan’s military aircraft and submarines with glow-in-the-dark gauges and depth meters. Once the war was over, Nemoto turned his attention to the civilian market.

Touring Japanese watch manufacturers and department stores, Nemoto demonstrated the usefulness of his product by painting phosphorescent coatings on the hands of wristwatches and wall clocks – illustrating how people could now tell the time even in the dead of night.  

The tactic worked. One of Japan’s largest watch and clock corporations agreed to send a series of dial plates to Nemoto, who applied them with luminous paint from a small workshop next to his house. The trouble – though no one considered it much of a problem at the time – was that early luminescent paints, or ‘lumes’, relied on radium to trigger atomic reactions within their phosphorescent pigment bases. It was the release of photons from phosphorous materials, typically zinc sulphides in the case of watch lumes, that caused luminescent paints to glow. Radium is, of course, radioactive.

By the late 1950s, following the Daigo Fukuryū Maru disaster – when a US-led nuclear weapons test in the South Pacific exposed 23 crew members of a Japanese fishing boat to acute radiation poisoning – the world had cottoned on to the harmful effects of radium on the human body.

By 1960, Nemoto & Co had abandoned radium, developing a new luminous material that emitted light through less harmful, though still radioactive, promethium. Innovations in chemical compounds continued until 1993, at which point the company struck gold – or, more accurately, stumbled upon the non-radioactive, non-toxic qualities of strontium aluminate.

Rather than self-generate light in the same way as radioactive paint, Nemoto & Co’s new substance, which it christened LumiNova, was capable of absorbing light from either ultraviolet or artificial sources. It would then release the energy as a fluorescent glow that diminished over several hours. Luminova proved to be brighter and more longer-lasting than any previous zinc-sulphide-based lumes.

Shortly after LumiNova was invented, RC Tritec AG, a company based in Appenzell, Switzerland, signed a contract with Nemoto & Co allowing it to produce and distribute the fluorescent substance under the name Super-LumiNova. Despite the crowing prefix suggesting otherwise, the phosphorescent materials are the same, except for the fact that one is Swiss-made, the other not.

It is the Swiss-made variant, naturally, given that the brand’s watchmaking facilities are based in La Chaux-de-Fonds, Switzerland, (the company itself is headquartered in Paris) that constitutes the crowning feature of Bell & Ross’s new BR03-92 Diver Full Lum.

BR 03-92 Diver Full Lum

Watchmakers, for the most part, tend only to apply lume to the hands and numerals of their timepieces, ensuring that these are the elements that glow in the dark. Bell & Ross, which last year brought out a watch with a florescent strap, has gone one step further – applying Super-LumiNova not just to the hands and indices of its BR-03-92 Diver Full Lum, but its entire dial.

Of course, a watch whose hands and indices match the colour of its dial exactly, wouldn’t be of much use, especially underwater, where it tends to get dark, fast. To ensure the legibility of its latest dive watch, Bell & Ross has applied it with two different grades of Super-LumiNova, each of which glows with a different intensity.

The Super-LumiNova used on most watch dials, to get properly technical, tends to be C3, a yellowish-green lume that emits the brightest glow. It is C3 that Bell & Ross uses for the hands, hour indices and bezel markers on its BR 03-92 Diver Full Lum. For the watch’s dial, the company employs a different pigment – C5, which glows slightly greener, and is marginally less florescence.

Contrasting against the watch’s green-on-green face, is a 42mm square case cut from matte-black ceramic. A guard-equipped crown means that the timepiece is good to a depth of 300 metres, while a unidirectional rotating bezel and 60-minute diving scale ensures that you can track the time that’s elapsed while you’re down there. Choose between a black rubber or black synthetic canvas strap. A run of 999 BR 03-92 Diver Full Lum watches will be produced.

BR 03-92 Diver Blue Bronze

Alongside the phosphorescent Diver Full Lum, Bell & Ross has launched the more retro-looking BR 03-92 Diver Blue Bronze. While the use of Super-LumiNova on the watch’s hands and indices again ensures legibility underwater, the talking point of this timepiece is unquestionable the striking contrast between its blue-lacquered dial and bronze, satin-polished square case.

The watch debuted at Baselworld 2019 with an olive-green bezel, 42mm case, automatic movement and a guarantee that it was water resistant to 300 metres. The new watch shares the same specs but has been updated with a blue bezel and matching blue calfskin leather or blue rubber strap. It’s steel case-back features an engraving of a bronze, deep-sea helmet.

Like all bronze watches, the BR 03-92 Diver Blue Bronze will patina over time, meaning that every one of the 999 pieces being produced will acquire a unique appearance.  

BR03-92 Diver Full Lum, £3,800; BR 03-92 Diver Blue Bronze, £3,500, bellross.com