The large stone will be offered at its June sale along with a selection of secondary-type rubies from a new area of the Montepuez mine.
‘Holy Grail’ of watches expected to sell for $16M
The most complicated watch ever made entirely by human hand is expected to sell for up to $16.8 million at Sotheby’s this November when the timepiece makes its first reappearance on the market in 15 years.

With a total of 24 horological complications, the “Henry Graves Supercomplication” clockwatch was made by Patek Philippe in 1933 and is “the most famous watch in the world,” Sotheby’s said.
In 1925, New York banker Henry Graves commissioned Patek Philippe to produce the most complicated watch in the world, a project that took three years of research and five years of effort.
The gold open-face minute-repeating chronograph clockwatch features Westminster chimes, as well as a perpetual calendar, moon phases, sidereal time, power reserve and indications for time of sunset and sunrise, as well as an illustration of New York’s night sky.
“Indisputably the ‘Holy Grail’ of watches, the Henry Graves Supercomplication combines the Renaissance ideal of the unity of beauty and craftsmanship with the apogee of science,” said Tim Bourne, worldwide head of watches at Sotheby’s.
The clockwatch retained the title of the world’s most complicated watch for 56 years but eventually was surpassed by technicians working with the aid of computer-assisted machines. It still remains, however, the most complicated watch ever made completely by hand.
Sotheby’s first sold the Henry Graves Supercomplication for $11 million in New York in December 1999, part of the auction house’s Time Museum sale. At the time, the sale marked the most expensive timepiece ever sold at auction.
The Henry Graves Supercomplication now will be part of Sotheby’s Geneva Nov. 11 sale of Important Watches.
Editor's Note: Sotheby's had incorrectly reported date of its Important Watches sale as Nov. 14. The correct date is Nov. 11.
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