Christian Klien’s race in Monaco lasted one lap. His team’s $300,000 diamond lasted somewhere between a few hundred meters and a corner.

The Austrian rookie made contact with one of the Jordan cars exiting Mirabeau on the opening lap of the 2004 Monaco Grand Prix. His front wing broke, his Jaguar slid down the hill, and he came to rest in the barriers at the Loews hairpin. By the time anyone from the team reached the car, the diamond that had been fitted to the nose was gone.

It has never been found.

A PR plan that was supposed to be unmissable

Jaguar Racing’s director of communications at the time, Nav Sidhu, had negotiated a deal with the diamond house Steinmetz to fit a real stone to each of the team’s two cars that weekend. Mark Webber had one. So did Klien. Together, the two gems would be worth around $1m today, the BBC reported.

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The branding was also tied to Ocean’s Twelve, the Hollywood film in which an international diamond heist drives the plot. George Clooney, Brad Pitt and Matt Damon were on the grid that Sunday.

The then team principal, Tony Purnell, told BBC Sport that the package was essentially unbeatable publicity for a midfield team.

The moment the stone disappeared

Sidhu told the BBC’s podcast that his first instinct when the crash unfolded was not what it should have been.

“At that point, I probably should’ve been worried about the car or the driver. But, I must admit, my immediate thought was for the diamond,” he told BBC Sport.

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He got to the scene as fast as he could. The stone had already gone. Nobody at Jaguar has ever been able to pinpoint the moment it came loose: on contact at Mirabeau, somewhere on the slow slide down to Loews, or in the long window during which the wrecked car was retrieved. Webber, whose own car still carried its diamond, retired later in the race with a gearbox issue and brought his stone home.

The theories that have never been settled

The missing diamond was button-sized and set in a stainless-steel carrier bonded to the nose cone. Jaguar’s working assumption, Purnell told BBC Sport, is that a spectator or marshal pocketed it in the confusion.

He has also entertained less glamorous scenarios: a Monte Carlo street sweeper, a storm drain, or a stone that shattered on impact and was carried away in pieces by passers-by. Sidhu, on the podcast, still leans toward the pocket theory.

Steinmetz, which supplied the stones, used the weekend to launch itself into the global motorsport spotlight and never publicly complained about the loss. In 22 years, no auction house, no insurance adjudication and no anonymous collector has openly surfaced a loose 1.4-carat diamond with Monaco provenance.

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What became of the team that lost it

Jaguar Racing never raced in Monaco again. Ford sold the operation to Red Bull at the end of the 2004 season, and the energy drink firm has since built what was once a struggling midfield outfit into one of the dominant forces in modern Formula 1.

The diamond itself has no such second act. In 22 years, nobody has publicly returned the stone, claimed to have found it, or produced any 1.4-carat gem with Monaco provenance. The case is open on the BBC’s new podcast; the Steinmetz stone remains unaccounted for.

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