The Patek Philippe Grand Complication Sky Moon Tourbillon is the most expensive watch ever sold on an online auction. The price he got? $5,815,300. The sale took place on March 21 at Christie’s Top Of The Time auction in Hong Kong.

Why are these hours so important? Patek Philippe created the Sky Moon Tourbillon, Ref. 5002 in 2001 and was the most complex double dial wristwatch ever made.. The aim was to combine the most interesting complications in the limited space of wristwatches, twelve in all: a perpetual calendar with retrograde date, cathedral minute repeater, tourbillon, sidereal time.

On the reverse side is a full image of the night sky with the movement of the stars, the orbit of the moon and the phases of the moon. The Sky Moon Tourbillon presented at auction featured a fully engraved 44mm white gold case. It was built in 2015.

Other notable watches that sold for a much higher price than appraisers predicted include:

PATEK PHILIPPE Grand Complication art. 5208P-001

Year of issue: 2015. Features: minute repeater, perpetual calendar, one-button chronograph, moon phases, leap year indicator and day/night indicator.

Sale price: $999,541

GERALD GENTA Minute repeater Perpetual calendar

Impressive platinum skeleton watch with chime, perpetual calendar, leap year indicator and moon phases.

Selling price: $104,791 (at least five times the lowest estimate).

ANDERSEN GENEVE Unique item

Year of issue: 2015. One-of-a-kind 18K white and rose gold watch designed by Jean-Pierre Hagman with 21K blue gold tapestry dial, Art Deco hands, historic LeCoultre 1920 minute repeater movement ‘s, a perpetual calendar with a leap year indicator at number 6.

Selling price: $45,141 (at least seven times the lowest estimate).

JAEGER LE-COULTRE Reverso with tourbillon and power reserve

Reversible model in 18K rose gold with tourbillon and power reserve indicator. Collector’s edition of 500 pieces.

Selling price: $45,141 (double the lowest estimate).