Two men in hoods and armed with knives robbed the Kronometry jewellery shop, on the famous Croisette opposite the site of the Cannes Film Festival, in broad daylight on Wednesday morning.
The value of their booty was not known by midday Wednesday.
The shop was robbed in February when thieves who gained access via a neighbouring building took just 10 minutes to steal about 150 watches at an estimated worth of one million euros.
On Sunday a man armed with a pistol robbed jewellery worth at least 103 million euros, beating the previous world record of 100 million euros from an exhibition put on by the Leviev company at the Carlton hotel.
The previous record is believed to be a robbery in at the Diamond Center in Antwerp, Belgium, in 2003 where the booty was worth about 100 million euros.
In May thieves stole jewellery that was to be leant to film stars from the room of an American employee of Swiss jeweller Chopard.
Also during the festival, robbers made off with a diamond necklace and at least two apartments rented by film executives were burgled with thieves taking cash, jewellery and other personal items.