Of course, there’s no arguing that Patek Philippe sits atop the watchmaking pinnacle as the finest manufacture in the world.

But while Patek is renowned for its superb in-house movements, it should be noted that up until fairly recently, even its complicated chronographs used source Swiss calibres from the likes of Lemania, and before that, Valjoux. Of course, these were superbly finished versions of ebauchés, but this is old-school watchmaking in a nutshell: A maison such as Patek would source the parts from the very best manufacturers, and in the 1980s, 1990s, and early 2000s, that was Lemania.

The Reference 5970J we have here is a yellow gold version of a perpetual calendar chronograph produced between 2004 and 2010, preceded by the ref. 3970 and succeeded by the ref. 5270. It’s powered by the Calibre CH 27-70 Q manually-wound movement — Patek’s modified version of the Lemania Calibre 2310. Hand-finished and beautiful, it formed the basis of not only this watch, but also the Calibre 321 used in the first Omega Speedmasters. 

What is this notable movement powering? Namely, a dial with an incredible amount of information, conveyed in an elegant form that only a maison such as Patek Philippe could design: On its beautiful silvered face with applied white gold indices, there are dual day and month displays beneath the 12:00 index; a combined 30-minute totalizer and leap year indicator at 3:00; a combined date wheel and moon phase indicator at 6:00; and a combined running seconds and 12-hour totalizer at 9:00. (And yes, the 5970J also tells the time.)

Housed in a beautifully finished 40mm case, this "J" variant watch in yellow gold is among the rarest of the 5970 production. It comes fitted to a signed black alligator leather strap with a signed, 18K yellow gold deployant clasp.

Generously sized with a gorgeous dial and featuring one of the most notable chronograph movements in history, we’ll be damned if this isn’t one of the most stunning complicated watches we’ve ever had the pleasure to offer.