Cartier Ballon Bleu de Cartier 40 mm WSBB0040

Imagen: Cartier, web oficial

The storyWhy this reference matters

The Ballon Bleu came out of Cartier's manufacture at La Chaux-de-Fonds in 2007, at the height of a fashion for watches piled high with complications and decoration, and the president of the day defended it as exactly the opposite: a return to simplicity. It was a risk. Cartier was the house of watches that are not round — the Tank, the Santos, the Tortue — and here it was walking into the most crowded corner of the industry with a round watch nobody had seen before.

The design idea is not in the outline. It is in the crown. Rather than bolting on a guard, Cartier made the case swell over it in one continuous arc, so the blue cabochon appears to float inside the metal. To make that work, the dial had to give ground: the minute track drops in towards the centre across that stretch and the Roman numerals squeeze up around it. That asymmetry is the model's signature, and it is where the name came from.

The hidden signature sits in the VII — the Cartier logo camouflaged inside the numeral, the mark the house uses to identify its own work. Inside is the 1847 MC, born in 2015 when ETA stopped supplying brands outside the Swatch group: 23 jewels, 28,800 vibrations per hour, about 40 hours of reserve. That movement is 3.8 mm tall. Which tells you the 12.4 mm of total thickness has nothing to do with the mechanism and everything to do with the curve of the case.

SpecificationsThe numbers, in one table

IdentificationHow to tell it apart

This is the 40 mm at 12.4 thick, steel case, silvered guilloché dial with black Romans and blued sword hands, date window on the crown side, steel bracelet. Cartier sells the same size with other dials, a green one among them, and on a strap rather than a bracelet. The WSBB0040 is the silvered dial on metal.

The quick check is on the right-hand flank. The arc over the crown should come out of the case with no visible join, as though the metal had simply been drawn outwards; the crown itself is fluted and set with a blue synthetic spinel cabochon. If that arc reads as a part somebody attached, or the cabochon is loose or chipped, the watch has been got at.

Be careful about water resistance, because the watch looks tougher than it is. Steel bracelet, forty millimetres, and the official figure is 3 bar. Thirty metres, with no screw-down crown. That is the most practical difference between this and a Santos from the same house, which is rated at a hundred.

CollectingWhat collectors check

The Ballon Bleu case is curved and almost entirely polished, which is a cruel combination. It picks up hairline scratches from being looked at, and it cannot be refinished without the risk of flattening the curve. Turn one towards a window before you decide anything. A case that has been through unskilled hands loses its rounded volume, and that volume is precisely what you are paying for.

The weak point is the crown arc. It projects from the right-hand flank, which is exactly the part of the wrist that meets door frames and the corners of tables, so look along that curve for knocks and flat spots. And with no screw-down crown, pull it out and push it back a few times and feel that it runs cleanly in both positions. At a rated thirty metres, a tired gasket has no margin whatsoever.

Last, the height. Twelve and a half millimetres on a 40 mm round case with that dome is felt on the wrist far more than the figure suggests, and the watch sits high. Try one on. No exceptions. A good proportion of the quick resales of this model come from people who bought it from a photograph.

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