Reference 57260

The Vacheron Constantin Reference 57260 is a single highly complicated mechanical pocket watch, featuring 57 complications. The watch was assembled by Vacheron Constantin and introduced in 2015. The company claims that it is the most complicated mechanical pocket watch ever created—followed up by Patek Philippe Calibre 89 assembled in 1989 and featuring 33 complications. The Reference 57260 took eight years to assemble. The watch has 2826 parts and 31 hands, weighs 957 grams, and spans 98mm.
The Reference 57260 is one of Vacheron Constantin's tailor-made pocket watches with grand complications. Members of the lineage include James W. Packard's minute repeating pocket watch (1918), which was auctioned for US$1.763 million by Christie's in New York on June 15, 2011, and King Fuad I's pocket watch No. 402833 (1929), which ranks as one of the most expensive watches ever sold at auction, fetching US$2.77 million (3,306,250 CHF) in Geneva on April 03, 2005. In addition, in 1946 Vacheron Constantin made a customized pocket watch for King Farouk of Egypt, the successor of King Fuad I, and in 1948 the company tailored another pocket watch for Count Guy de Boisrouvray of France. 
Price.
The price agreed between the company and the client is confidential and has not been officially disclosed; however, various sources estimate the price to be in excess of $10 million. It was built for a single client, whose personal details are kept confidential and is only described as "A major watch collector".