Review: Deep dive with the De Bethune DB28GS Grand Bleu

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The DB28 GS Grand Bleu, the first diving watch by De Bethune. Equipped with a mechanical lighting device using 4 LEDs. We get hands on and analytical.

De Bethune DB28GS Grand Bleu

De Bethune presents its first sports watch with the DB28GS. Not only a new case with a water resistant rating of 105m, but also a new movement and a novel way to provide readability in the darkest depths with a photoluminescent blue material within the movement.

The case, dial and hands

First the case. Built in titanium, the case is water resistant to 105m. A strange number, one may ask. This depth rating is inspired by Denis Flageollet’s fascination with the Luc Besson French movie – Le Grand Bleu, where the hero dives to a depth of 105m. The case features all the touches of a De Bethune – refined, yet sporty and strong. The hand polished titanium shows as a rather soft finish which is plush to touch.

It features the De Bethune patented system of floating lugs to adapt to wrist size and movements. The lugs are completely redesigned for the DB28GS in a medium size tailored to the sporting spirit of the watch. The famous cones at the lug sides are prominent, and adorned with black zircronium inserts.

The dive timing mechanism is by means of the standard rotating bezel, first appearing in about 1952. But the DB28GS does this with a twist. The bezel rotates, but the indications appear on the sapphire crystal driven by the bezel. This enables the watch to take on a more slender and elegant persona, instead of a huge bezel, it presents a sleek one.

The dial does not really exist, and what one gazes on from the face of the watch is the movement, which is proudly displayed and decorated. The famous De Bethune shield takes the central position, and features raised side edges which are highly polished, and micro light concentric circles engraved on the inner. A satin-brushed grade 5 titanium minutes annular dial is at the circumference and is punctuated with cut-out Arabic numerals.

The hour hand is huge. Built from blued titanium with a polished steel insert, it looks like a part from a high torque machine, first used by De Bethune in the DB22 and DB24 Power. The minute hand is in the form of a blued titanium arrow. Both are tipped with Superluninova. The seconds hand is in polished stainless steel with a luminiscent tip, and centrally pivoted. A power reserve indicator is tucked behind the De Bethune signature shield dial between 9 and 10.

The model is delivered with two straps: a canvas version and a striated natural rubber iteration with titanium folding clasp, which also contributes to the practical and pleasant wearer comfort of this timepiece.

The lighting system

The DB28GS features an ingenious lighting system powered by pure mechanical forces to light up 4 LED lights placed within the watch.

The basic principle is similar the humble bicycle dynamo. Fully mechanical with no electronics and no battery. A pusher at 6 o’clock activates a small gear train driven by the twin barrel. This gear train, by means of a miniature dynamo, provides the necessary energy for lighting the watch. A few seconds of light is more than enough to read the time, even in the middle of the night, or the depths of the ocean.

We do note that this is not the first time this technique of lighting is used in a watch. HYT first pioneered this concept in their H4 Alinghi. While we have not studied the technical drawings and construction details, De Bethune has claimed this dynamo as their 2019 innovation, so presumably the operating principle is different from the one used by HYT.

The main research is in finding a crystal which has the iconic De Bethune blue in natural light, and radiates in a luminiscent blue of the same hue in the dark. This exclusive luminescent material, named Blue Moon, was developed in partnership with the Swedish company Black Badger Advanced Composites (James Thompson) in collaboration with Swiss SuperLuminova™ and is now proprietary to De Bethune.

Official De Bethune press photograph.

Photo note: The official Press photographs released by De Bethune feature digital manipulation to show the final result of this blue. And our own photographs which you see here are offered with no digital imaging touch ups, and what we saw with the flash lighting we used to photograph the watches. We do note that as the research on the material is on-going, the final watches which are delivered may look closer to press photographs.

The movement: DB2080

The movement is the new DB2080 movement. Handwound, five day power reserve indicated on the dial, this is the 27th calibre entirely developed and manufactured by the Manufacture De Bethune, equipped with a state-of-the-art in-house-made balance wheel. The movement is visible from the front as well as from the back.

The case back of the De Bethune DB28GS.

The titanium and white gold balance wheel with a balance spring equipped with a flat terminal curve beats at 28,800 bph. It is endowed with numerous properties – such as optimised efficiency, reliability, regulating quality, thermo-compensation, anti-magnetism – leading to concrete results, since De Bethune has already improved the efficiency of its sprung-balance-escapement ensemble by achieving a 20% increase in power reserve.

The calibre is also equipped with the triple pare chute system. De Bethune was not only the first to design a bridge symmetrical held on both sides and thus serving to maintain the balance wheel perfectly in position, but also added two shock absorbers on either end as well as that of the balance wheel itself. Hence the name triple pare-chute.

The balance bridge, with the triple parachute system.

Movement finishing is typical of De Bethune, a very high level of finishing in DB’s own style. This is not a traditionally finished haute horlogerie watch, though the level of finnisage and detailing is no less. The final finish is at once very technical and very engineering looking, but also very fine and elegant, extending from the case, lugs, dial or absence thereof, the entire movement and the hands.

Competitive Landscape

Interestingly, for a watch with this level of achievement to build a mechanically operated lighting system, the landscape is not barren.

In it, a similar system lives within another highly creative independent brand. We speak of the HYT H4 Alinghi and the H4 Metropolis. The Alinghi is retails at S$136,000 (S$99,000) and the Metropolis at S$127,000 (CHF 92,000) inclusive of GST. The DBS28GB is priced at CHF 85,000 before taxes, which work out to be about S$124,800 with GST, direct conversion from CHF to SGD.

HYT H4 Alinghi with the LEDs activated, in the dark. The white light bathes the entire movement and the time can be read clearly. Not something which is easily done in the dark with the H1 as the liquid does not take to addition of a luminous substance. Note the light spill from the LEDs, creating a beautiful background for the watch. Very cool.

The HYT system is similar. Wind the crown, and it winds a spring which is part of the dynamo system. 89 components squeezed in the space of the small curved space below the bezel. Two LED lights below the 6 lights up when the spring is released. On full wind the spring can power the two LEDs for about 12 seconds, available in 5 second intervals with each push of the crown.

Concluding thoughts

The De Bethune DB28GS Grand Bleu cuts an imposing figure on the wrist. But it no less comfortable, thanks to the ingenious lug design and the the light titanium case. The wrist presence is unmistakable, and from a distance, the DNA signals to anyone and everyone that this is a De Bethune, and the owner is a person of taste. Not only oozing in good taste, but also one which is a well developed palate raised with a diet of the good things in life.

At CHF 85,000 this is not an impossibly expensive watch which most can only drool over. The price is very similar to the HYT H4 Metropolis, though of a decidedly different aesthetic. The DBS28GS is a magnificent example (as is the HYT) of precision engineering and a keen sense of beauty which one can strap on one’s wrist. True, this is no small money for a time only watch with power reserve, but this is a watch which is lavished with the attention and detailing of only the masterful Denis Flageollet can afford. And for that, we deem it worthy.

De Bethune DB28GS Grand Bleu Technical specifications

Name: DB28GS Grand Bleu

Reference: DB28GSV2AN Functions: Hours, Minutes, Seconds, Power reserve indication between 9 and 10 o’clock, unidirectional rotating bezel, manual dial lighting

Movement: DB2080

Type: Mechanical hand-wound movement Adjustment: Winding and setting the time by means of the crown (2 positions), push button at 6 o’clock to activate the lighting

Technical features of calibre DB2080

Number of parts: 400 Jewelling: 51 jewels Diameter: 30 mm Power reserve: 5 days, ensured by a self-regulating twin barrel De Bethune Innovation (2004)

Specificities: Titanium/white gold balance wheel with white gold inserts, optimised for temperature differences and air penetration De Bethune Patent (2016)

“De Bethune” balance-spring with flat terminal curve De Bethune Patent (2006)

Silicon escape wheel

Triple pare-chute shock-absorbing system De Bethune Innovation (2005)

Dial lighting produced by an entirely mechanical means working on the dynamo principle powered by a twin barrel and manually controlled via a pusher De Bethune Innovation (2019)

Frequency: 28,800 vibrations per hour Adornment: Mirror- polished grade 5 titanium motion-work bridge Plate and barrel bridge covers in hand-smoothed grade 5 titanium and adorned with “Microlight engraving” De Bethune Innovation (2007) Hand-snailed barrels Hand-polished and chamfered steel parts


Display: Blued titanium hours and minutes hands with polished steel insert and second blued steel insert, luminescent tip Polished steel seconds hand with luminescent tip Power-reserve indicator between 9 and 10 o’clock

Dial: Satin-brushed grade 5 titanium minutes dial with cut-out Arabic numerals Rotating bezel crystal with metallised minutes ring

Case and strap

Case material: Black zirconium case middle with “Microlight” decoration, brushed and polished grade 5 titanium caseback and bezel Case diameter: 44 mm Case thickness: 12.8 mm Lugs: Floating lugs in brushed grade 5 titanium – De Bethune Patent (2006) Crystal: In sapphire crystal (1800 Vickers hardness) with double antireflective coating Case back: Open in brushed grade 5 titanium Water resistance: 10 ATM Strap: Natural rubber strap + 1 canvas / leather strap Buckle: Folding clasp in brushed grade 5 titanium


1 Comment

  1. Thank you for the review. While I like the watch generally (and your photos are particularly great in this article), I’m afraid I can’t get over the LED lighting. The LED makes the watch look a bit cheap, like your average consumer electronics item.