Ryder reportedly borrowed the Bulgari jewels to wear to a Marie Claire magazine party this week, then said she left them with her hotel's front desk for safe keeping. Now, it seems, they are missing, the Post said.
The French magazine Voici said there is no security camera footage showing Ryder handing over the baubles to the hotel staff and reported that Bulgari has asked Madrid police to investigate their disappearance.
The Post noted in its account of these recent events that Ryder has a history of shoplifting. The newspaper also said the actress' representatives did not return its messages asking for a comment on its story.
Ryder is best known for her roles in "Lucas," "Beetlejuice," "Heathers," "Little Women," "Edward Scissorhands," "Bram Stoker's Dracula," "The Age of Innocence," "Reality Bites," "Girl, Interrupted" and "Mr. Deeds."