In medicine, business and relationships, complications are a best avoided. But in watches, complications are better than jewels.

As if to prove the point, Patek Philippe, the storied 174-year-old watch-maker, is releasing its most complicated watch ever. And that's saying something, since Patek is considered the master of fine watch complications.

The watch is called the Reference 6002 Sky Moon Tourbillon. It's got 12 complications—making it a "Grand Complication," including a tourbillon, minute repeater, sky chart and perpetual calendar. The sky chart on the back of the watch shows the evening sky in whatever region you happen to be in, while the moon-phase display shows you whether the moon that night is a crescent or full.

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The watch took seven years to develop and make, and the engraving alone takes more than 100 hours. The minute repeater has a chime that's tuned to sound like cathedral bells.