Kim Kardashian West's Paris robbers used a decoy to escape.
Police investigating the theft reportedly discovered a tiny gemstone close to the residence on Sunday, but now think it might be a decoy used to make police "believe that they were amateurs".
A police official told Us Weekly magazine: "They wanted us to believe that they were amateurs, but all the real clues point to them being extremely sophisticated professionals.
"There is no way a gang like this would drop stuff and fall off bicycles - all that was done for any cameras that might be in the area. It is far more likely that they played around on bikes for a few minutes after stealing the jewels, and when they still had their masks on, before they all got into a van and disappeared."
The source explained that the burglars set up a "double bluff" in which one of the five men fell off his bicycle whilst another pretended to drop a piece of jewellery as they fled.
The gem that was found was reportedly of much lower worth that the rest of the haul, which the source said was because it was part of their escape plan, and so they chose a lower valued item to drop.
It was previously reported that police were hoping the dropped gem would lead to the capture of the criminals, as they hoped it would mean the gang made more mistakes along the way.
A source said previously: "A piece of stolen jewellery was found close to the block, and was presumably dropped by the gang. It suggests that the criminals may have made mistakes because they were in such a hurry."