A £750,000 Cartier ring has only just been registered as missing by the British Museum despite reportedly being lost since 2011.
Details of the loss were not made public until the publication of accounts from the Department for Digital, Culture, Media and Sport.
The report said: “During the year, one item from the collection valued at £750,000 was declared lost under the Procedure for the Reporting of Unlocated and Lost Objects. It has been written off in these accounts.”
The ring, which is a 20th century diamond and platinum piece, went missing in 2011 and police were called in to investigate but no further action was taking and the ring has since been declared as “lost”.
The ring was given to the museum by an anonymous donor.
A spokesperson for the British Museum said: “The ring was found missing from its proper location by British Museum staff in August 2011.
“It was reported at the time to the director and board of trustees and the police, who did not take the matter further. Thorough searches were undertaken at the time and subsequently.
“British Museum procedure, as agreed by trustees, requires the ring formally to be reported as lost five years after the initial discovery of its absence. The museum takes the security of the collection extremely seriously.
“The museum has since reviewed its security and collections management procedures and dedicated significant investment to improved security across the estate.”