A scrap metal dealer who bought a golden egg at a US bric-a-brac market discovered it is an ultra-rare Faberge egg worth around £20 million.
The unnamed buyer purchased the egg for £8,000 in the Midwest in the hope he could cash in on its scrap metal value.
But the striking object was saved from the melting pot because no-one recognised its potential by offering him more than he paid for it.
The egg became a financial burden to its owner who was unaware that it was a magnificent Third Imperial Faberge Easter Egg made for Russian royalty.
The egg, which contains a Vacheron Constantin watch inside it, sits on a jewelled gold stand and was given by Alexander III to his wife Empress Maria Feodorovna in Easter 1887.
In despair one evening, the owner tapped "egg" and "Vacheron Constantin" into Google and a newspaper article emerged about its background.
The article, published in the Daily Telegraph, quoted Kieran McCarthy, director of Wartski, the London-based Royal Warrant-holding experts on Carl Faberge's work.
Unable to sleep for days after recognising the egg as his, the owner flew to London to show images of it to Mr McCarthy who was left speechless.
To confirm it was not a fake, Mr McCarthy flew to the small Midwest town where the owner lived so he could be sure the egg was genuine.
When Mr McCarthy saw it on the owner's kitchen table beside some cupcakes, he confirmed it was the lost Imperial treasure.
Wartski bought the egg for a private collector who has allowed it to be displayed for four days at an exhibition at Wartski in London from April 14.
Mr McCarthy said: "It's the most incredible discovery. We have so many discoveries but none of them are as momentous as this.
"It has travelled from Imperial St Petersburg to the rust belt of America. It's a story that deserves to be told because it could so easily have slipped away.
"For the Faberge community and the historical community, it is a wondrous event because the Easter egg is the ultimate target for every antique dealer and every enthusiast."
He added: "It may never be seen again and it may disappear into the deepest, darkest vaults of a collector somewhere."
The egg was last seen in public in March 1902 when it was shown at an exhibition of the Russian Imperial family's Faberge collection in St Petersburg.
In the turmoil of the Russian revolution, the Bolsheviks confiscated the valuable egg from the empress.
It was recorded in Moscow in 1922 when the Soviets decided to sell it as part of their policy of turning "treasures into tractors".
Its fate afterwards was unknown and it was long feared that it could have been melted down for its gold value and lost forever.
But in 2011 Faberge researchers found the egg had been sold in New York in March 1964 for just £875 at the time.
It followed the discovery of an old Parke-Bernet catalogue, and it was sold as a "gold watch in egg form case" without its provenance being known.
The revelation sparked a worldwide race to discover its whereabouts, which ultimately led to the scrap metal dealer in America's Midwest.