The value of jewels stolen in the resort of Cannes on Sunday has been raised to about 103 million euros.
A man wearing a mask and carrying a pistol took the gems from an exhibition of diamonds at the Carlton Hotel.
Earlier the stolen gems had been given an estimated worth of 40 million euros.
The thief helped himself to diamond watches, necklaces and earrings from an exhibition on the ground floor of the hotel and left on foot.
The BBC reports hotel staff have complained about inadequate security at the exhibition, saying it was held in a wing that had direct street access.
Police also say they had not been alerted that the exhibition was taking place. The Carlton is located on the Croisette promenade.