This Rare Cartier Clock Could Fetch Over $6M in Upcoming Auction

By Annie Davidson Watson | September 16, 2025

A Cartier Portico mystery clock, one of only six such models in existence, will make a rare appearance on the auction market during Sotheby’s Important Watches live sale in Geneva on Nov. 9.

The clock, whose Asian-inspired design incorporates details from temples such as columns and a lion statue, has an estimated value of 3 million to 5 million Swiss francs (CHF), approximately $3.79 million to $6.32 million. It has remained in the same family since 1978.

Sotheby’s will exhibit the clock during Geneva Watch Days prior to the auction. In a statement, Sotheby’s global chairman of watches, Sam Hines, called the upcoming sale a “landmark moment in the world of horology and in collectors’ circles, given how extraordinarily rare Cartier Portico mystery clocks are at auction.

“To present this 1923 model, one of the earliest in the six-strong series ever created, for the first time in nearly 50 years is not only a privilege but also an event of remarkable importance, especially to international collectors,” Hines said.

The defining feature of mystery clocks is the illusion that the hands float freely, with no visible connection to the movement, on a translucent dial. Cartier horologist Maurice Couët perfected the concept for the luxury brand in the early 20th century, inspired by the genius of Jean-Eugène Robert-Houdin, the French illusionist-turned-watchmaker who created the first mystery clock around 1831. For the Portico model, Couët updated the design by hiding the entire mechanism within the dial.

With architectural forms and harmonious use of materials such as rock crystal, onyx, mother-of-pearl, and jade, Portico mystery clocks are works of decorative art that represent a pinnacle of horological ingenuity. These timekeepers are eagerly sought because of their technical mastery and artistry as well as their scarcity.

(Photo courtesy of Sotheby’s)

Follow me on Instagram: @anniedavidsonwatson