Cmdr. Bernard Mascarelli, a judicial police spokesman in the nearby city of Nice, said the robbery at the Novotel hotel overnight took place in the room of a representative of Swiss-based watch and jewelry maker Chopard.
The crime occurred just hours after the screening at Cannes of a film, based on a true story, about teens who broke into the homes of stars in Los Angeles to swipe designer bags, shoes and clothes from their homes.
The jewelry was "very probably" in the hotel in connection with the festival, Mascarelli said, though he didn't know who it might have been intended for. Chopard is a festival sponsor and has loaned jewelry to A-list stars who walk up the festival's famed red carpet under the rapid-fire flashes of photographers' cameras. This year model Carla Devigne and actress Julianne Moore have walked the carpet in Chopard gems.
Mascarelli said he didn't know the exact type of jewels taken or their exact value.
"Numbers have been put forward that we're still trying to verify, but the figure of $1 million ... we're in that range," he said.
Jean-Michel Caillau, the prosecutor in nearby Grasse who is leading an investigation, said early estimates were that the loot could have been worth as much as $1.4 million. He also said the theft appeared to have taken place around 2:30 a.m. Friday.
A Paris-based spokeswoman for Chopard, who declined to identify herself, said the company would not comment. Melissa Levine, a spokeswoman for Accor, the French hospitality giant behind Novotel, also declined comment. Dozens of police were involved in the investigation, and police vehicles could be seen outside the hotel Friday afternoon.
Authorities were going over hotel surveillance cameras and questioning potential witnesses who might have seen any culprits, and "it seems pretty unlikely to us that it was just one person," Mascarelli said.
"Apparently this (hotel guest) was someone who was targeted because it wasn't someone who had been seeking attention. ... There must have been either an inside complicity, or people who were in contact with this person and knew that the person had jewels," he said.
On Thursday night, Chopard hosted a star-studded gala, and the festival screened Sofia Coppola's "The Bling Ring" - a deadpan drama about celebrity-obsessed teenagers in Los Angeles who break into the homes of Paris Hilton and other stars. It's based on a true story about high-school students who, after seeing online when certain stars are expected at a premiere or other event, take the opportunity to steal items from their homes.
News of the robbery sent journalists scurrying to the Novotel, a business hotel about a 15-minute walk from Cannes' seafront promenade. It's decidedly less glamorous than the 5-star Hotel Martinez, where Chopard maintains a suite during the film festival. The company also manufactures the crystal and gold Palme d'Or trophy awarded each year to the festival's top film.
Festival organizers would not disclose the Palme's whereabouts Friday, but said it was kept in a safe place.
The festival had no comment on the robbery.