The thieves have been operating on the southern French coast since mid-July.
They count among their victims a Russian who was robbed of his 550,000-euro "Richard Mille" timepiece as he returned to his Cannes weekend home in a Bentley.
The gang's modus operandi involves identifying the owners of valuable watches and then following them to their cars.
As they prepare to drive off, one of the gang whizzes past on a scooter and deliberately clips the car's wing mirror.
When the driver reaches out to put it back in place, a second scooter arrives and the passenger wrestles the watch from the unsuspecting victim's
Police believe the robberies are the work of a gang from Naples, Italy that was behind a string of similar thefts in Cannes between 2007 and 2009.