Cannes Diamond Heist Value Up to $136 Million Diamond jewelry was in one bag and about to be put in secure display cases.

July 29, 2013 -- The value of the Cannes jewelry heist was more than doubled today to $136 million as fresh details of the daring robbery emerged.

The brazen theft occurred about 11:30 a.m. Sunday at the Carlton Intercontinental Hotel before the exhibition opened to the public and as the jewelry was about to placed into secure display cases, Deputy Prosecutor Philippe Vique told ABC News.

At the time of the theft, the diamond encrusted jewelry was in two bags and those bags were both placed inside another bag. Vique declined to say where the bag was at the time of the robbery.

The thief entered through a glass door off of Cannes' main street the Promenade de La Croisette, but the door was not smashed or broken and investigators are looking at surveillance cameras to determine how he was able to open the door, Vique said.

The suspect, wearing a scarf and a hat, pulled a semi-automatic pistol, grabbed the bag of jewelry and "jumped" through another glass door that was opened and that led to the Rue Einesy, the prosecutor said. While escaping, some of the jewelry spilled on to the street.

Despite dropping some of the heist, Vique raised the estimated value of the loot - all newly fashioned diamond jewelry -- to $136 million.

At the time the gunman came into the room, there was the exhibition's manager, two employees and three unarmed security guards, Vique said.

Cannes Police Officer Maurice Alibert told ABC News that the suspect spoke "perfect French."

"We think he is French," Alibert said.

Vique said it would be difficult to sell the hot jewelry because each item is "incredibly expensive."

It was the third such heist in the French Riviera resort in as many months.

The exhibit of jewelry was by the prestigious Leviev diamond house, owned by the London-based Russian Israeli billionaire Lev Leviev. The exhibit had been due to run until the end of August.

The Carlton hotel dominates the exclusive Promenade de la Croisette that stretches a mile and a half along the French Riviera.

It was a movie set hotel for "To Catch a Thief," the 1955 Alfred Hitchcock romantic thriller starring Cary Grant as a former jewel thief and Grace Kelly as an American heiress on holiday in the Riviera with her mother.

The Carlton itself was already a scene of one of the biggest diamond robberies, in August 1994, when a group of thieves firing machineguns burst into the hotel's jewelry store and made off with some $60 million in diamonds.