Vacheron Constantin introduced three chronographs at SIHH 2015, all presented in the new cushion-shaped Harmony case, with the top of the line model being the Harmony Ultra-Thin Grande Complication Chronograph. It’s a split seconds monopusher chronograph with a power reserve indicator, with the beautifully executed calibre 3500 inside.

The dial of the Harmony split seconds is silvered, with blue numerals and a red tachymeter. With the Harmony design being based on a 1928 VC chronograph, the look is appropriately vintage.  Start, stop and reset functions of the chronograph are controlled via button integrated into the crown, while the split-seconds is activated by the button at two o’clock. At 42mm in diameter, the platinum case is somewhat large but not overly so. The overall visual effect of the watch is one of restraint.

From the back, however, the view is decidedly more lavish. The calibre 3500 is an unusual construction, combining a traditional split seconds chronograph movement (with column wheel, lateral coupling) with the modern invention of a peripheral rotor.

Instead of being mounted on the movement as a full or micro-rotor would be, the peripheral rotor is a slim ring that sits around the movement. This means the self-winding movement is just as slim as a hand-wound equivalent, since the rotor makes the calibre wider, but not thicker.

As a result, the calibre 3500 measures just 5.2mm high, making it the thinnest split seconds movement. It’s also 0.05mm slimmer than the magnificent Patek Philippe rattrapante calibre CHR 27 (found in the refs. 5959 and 5950) which nonetheless has a smaller diameter than the VC movement. Decorated with a floral fleurisanne engraving common to all the Harmony watches, the gold mass of the rotor is screwed onto a large, toothed gear that sits around the movement. Its teeth wind the barrel via a gear that sits just beside the balance wheel.

The winding gear that engages with the peripheral rotor

Naturally the screwed balance wheel is fitted to an overcoil hairspring, with a swan neck regulator.

The chronograph mechanism of the movement is beautiful in a manner that only traditionally  constructed chronographs can be. A mass of levers, springs and wheels cover the base movement, with the pincers for the split seconds standing prominently in the centre.

Instead of a steel cap over the column wheel, a traditional feature in many Geneva-made chronographs (the Patek Philippe calibre CH 29 is a good example), the both column wheels in the calibre 3500 are topped with a relief Maltese cross, the brand’s logo.

A column wheel that controls the chronograph

And another for the split seconds

Even the base movement underneath the chronograph mechanism is traditionally constructed, with separate cocks for the escape wheel and gears of the going train.

The logo of the Geneva Seal on the escape wheel cock

The calibre 3500 is arresting, with tremendous detail to admire. And it’s hallmarked with the Geneva Seal, a testament to its decorative and functional excellent. However, up close, and I mean exceptionally close, the finest and most minute details of the decoration appear to be a hair’s breadth away from what Patek Philippe does, especially with the refs. 5959 or 5950, its equivalent of this VC. In the VC calibre 3500, the polished bevels are not quite as sharp, nor the inward corners of the components as pronounced.

But a head-to-head comparison is not entirely fair, since the Harmony Ultra-Thin Grande Complication Chronograph is priced at US$369,200 or S$518,200. While that is a lot of money, the equivalent Patek Philippe 5950A costs almost US$100,000 more, despite having a steel case.

Only 10 of the Harmony Ultra-Thin Grande Complication Chronograph will be made, though it is likely the calibre 3500 or some variant of it will eventually make its way into other timepieces.