The tiara once belonging to Grand Duchess Hilda. Courtesy Badisches Landesmuesum.

A tiara decorated with 367 diamonds has been stolen from the Badisches Landesmuesum, a state museum in the city of Karlsruhe, Germany. The gold-and-platinum coronet, which dates back to 1906/07, was reportedly swiped from its large glass vitrine in broad daylight on April 29, with no eyewitnesses of the incident.

Police are seeking out anybody who might have details regarding the theft or the small crown’s current whereabouts.

The museum has remained relatively tight-lipped on the theft and following investigation, but acknowledges that the tiara was stolen from a display case in the throne room without any great force. “A suitable object” was used to open the case that remains intact, a spokesperson for the museum has confirmed. Details on how the robbers gained such seemingly easy access to the priceless object are unknown.

The tiara, which is valued at 1.2 million euros ($1.31 million), originally belonged to the Grand Duchess Hilda (1864-1952), and was worn at the reception celebrating the 80th Birthday of the King of Sweden before being passed onto the duchesses’s niece, Antoinette Crown Princess Rupert of Bavaria.

It was last worn by her daughter, Princess Edith, in 1956, at the wedding of Countess Helen Toerring-Jettenbach to the Archduke of Austria.