The crown of French Empress Eugenie was left crushed after being dropped by fleeing thieves during a raid at the Louvre last October - but is nearly intact and can be fully restored, the museum has said.
Raiders stole an estimated 88 million euros (£76m, $104m) in jewels, but left the diamond-studded headpiece belonging to the wife of Napoleon III on their escape route.
The museum has issued the first photographs of the crown since the theft, saying it had been left badly deformed after the thieves tried to remove it through a narrow hole they sawed in its glass display case.
The crown is missing one of eight golden eagles that adorned it but retains its 56 emeralds and all but 10 of its 1,354 diamonds.
The 19th Century crown would be restored to its original state without the need for reconstruction. An expert committee led by the museum's president Laurence des Cars will oversee the restoration.
The heist took place on 19 October and involved a stolen vehicle-mounted mechanical lift, which the gang used to access the Galerie d'Apollon (Gallery of Apollo) from a balcony overlooking the River Seine.
Prosecutors revealed that the thieves managed to remain inside the museum for less than four minutes after threatening guards and cutting through two display cases containing royal jewelry.
Police have arrested four suspects in connection with the theft, while the mastermind of the heist remains at large. Meanwhile, seven other stolen items, including a tiara belonging to Eugenie, are still missing.
