A Collected Man sold an Philippe Dufour Grande et Petite Sonnerie watch for US$7.63 million within a day.

According to the site:
The present example is part of the highly restricted series of watches. According to ACM, “only eight examples have ever been made, with this one being the third to leave the watchmaker’s workshop, and unique in its configuration. Completed in 1995, it was first delivered to the Sultan of Brunei.” The Grande et Petite Sonnerie Wristwatch is also the first in Dufour’s series of watches, also comprising the Simplicity and Duality, and it has been crafted over the course of a decade throughout the 1990s. This watch certainly is a unicorn in the collecting world, which has been offered for sale on very, very rare occasions – one by Christie’s here for example. The present watch, Number 3, was auctioned by Sotheby’s in 2012, where it achieved HKD 4.82 million (or about USD 620,000).

Philippe Dufour

A super rare watch designed for a King is worth so much.

This has proven that:
Philippe Dufour Grande et Petite Sonnerie would become the most expensive watch made by an independent watchmaker to be sold publicly, as well as one of the ten most expensive wristwatches ever sold publicly.