Police said Wednesday it could have been the second theft from the museum by the same person.
Oakland police Lt. Oliver Cunningham says there are striking similarities between Monday’s break-in and the theft of gold nuggets and other historic artifacts in November.
Museum director Lori Fogarty says the jewel box was a wedding anniversary gift from a San Francisco man to his wife in the 1800s.
Oakland city officials have said the box was valued at more than $800,000.
Another Northern California museum and a county courthouse have also been hit by gold thieves over the past year.