Imperial Hue: De Bethune Introduces The DB28XS Purple Rain

The color purple has a history as long and rich as human civilization itself, and De Bethune’s latest watch – the DB28XS Purple Rain – is a connection to one of the most exotic and mysterious colors of the spectrum – and one which, throughout history, has had a rich, deep and varied symbolism.

The DB28XS Purple Rain is a follow-up to the DB28XS Starry Seas, which paired the DB28 case design, with its swiveling “floating” lugs and crown at 12:00, with a heat-blued titanium dial engraved with what De Bethune calls a “random guilloché” pattern, decorated with tiny gold stars intended to evoke starlight reflected on the surface of the ocean at night. (The intricate guilloché pattern is not entirely random, of course; a hint of that can be seen if you examine an individual ripple closely. You’ll notice that it’s bilaterally symmetrical along the central vertical axis of the dial). Purple Rain is the same dimensions as Starry Seas, at 38.7mm x 7.4mm – the XS is for Extra Slim – and the movement is the same as well, the De Bethune caliber DB2005. The color of Purple Rain is not only found on the dial, but also on the rehaut, case, floating lugs, and crown as well, all of which are made of heat-blued grade 5 titanium.

The purple color is carried through to the movement as well, which has a heat-colored, purple titanium baseplate with concentric Microlight engraving, and central bridge.

De Bethune is well known for its use of heat-blued titanium, of course, which is beautifully on display in a number of its other watches. This is the first time that the company has used heat-colored purple titanium, however. It’s always dangerous to call anything a first in watchmaking but I can’t recall any other watchmaker using titanium heat-colored to this particular hue before. Steel hands heat-tempered to purple rather than blue can be found in many 19th century pocket watches – some of them American made – but I don’t think anyone’s done this with titanium in watchmaking before.

It’s not unheard of for heat-colored titanium to show up in other places – jewelry making and knife making are two examples – but in general what you’ll see is a more or less random pattern of iridescent colors, rather than a single even shade. This is because it’s technically very difficult to get titanium to color evenly when heated. Like heat-colored steel, titanium transitions through a rainbow of colors as its temperature rises. The phenomenon is known as “interference color” and it occurs because as you heat the metal, the oxide layer on the surface (ordinarily so thin that it’s basically transparent, and which gives titanium its resistance to corrosion) starts to thicken. In doing so it begins to refract and reflect the light, like a film of oil on blacktop or the surface of a soap bubble or, more poetically, the wings of the Blue Morpho butterfly

The problem with titanium is that unlike steel, it’s a poor conductor of heat, which means that as you apply heat the metal tends to develop hot spots. To get the very even, consistent purple color in the Purple Rain, you have to heat the case (or lugs, or crown or movement plate) slowly and carefully, as the temperature range for purple is narrow.

The effect once achieved, however, is remarkable. The color purple is most famous historically for its use in dyeing fabric – the Romans had strict rules governing who could and could not wear purple-dyed togas, with top ranking magistrates being restricted to a single stripe at the hem of the garment. Only generals celebrating a triumph, and the Emperor, could wear a full purple robe. The reason is that the dye could only be made by processing the flesh of snails from a particular family (Murex) and it took 12,000 snails to make 1.4 grams of dye – just enough to edge one toga. A child of a reigning emperor was said to be phorphyrogenetis, or “born in the purple,” and the English word is ultimately derived from the Greek “porphura” which was the name of the Tyrian purple dye so prized in the ancient world.

The caliber DB2005 is like all of De Bethune’s movements, as distinctive technically as it is aesthetically. The highlight is the oscillator system. The balance is heat-blued titanium with white gold inserts, and the balance spring has the patented De Bethune terminal curve, which provides the symmetrical “breathing” of a Breguet overcoil, without the added height the latter requires. The whole oscillator system is mounted in De Bethune’s triple pare-chute antishock system, which adds additional shock resistance to the conventional antishock system on the balance pivots and which also helps the balance to center itself more rapidly if the watch does receive any sort of physical impact.

The slim, sub-39mm case and floating lugs make this an extremely wearable and versatile watch and of course, the combination of case design, movement design, and color make the Purple Rain unique – an aristocratic color for modern day watch royalty.

The De Bethune DB28XS Purple Rain: case, 38.7mm x 7.4mm, grade 5 titanium, with floating lugs and crown at 12:00, all heat-colored to purple; dial, heat-colored purple titanium with starry sky of white gold stars; sapphire crystals front and back; water resistance 30M. Movement, De Bethune caliber DB2005, hand wound, running in 27 jewels at 28,800 vph; six day power reserve via self-regulating twin barrel; diameter 30mm. De Bethune titanium and white gold balance with De Bethune terminal curve balance spring and triple pare-chute antishock system. Price, $99,000; limited edition of 25 pieces world wide. For more, visit DeBethune.ch.