The thefts took place at luxury hotels in Nice and Monaco on the sunny Côte d'Azur, in Evian in the Alps, in the central city of Lyon and in the chic suburbs of Paris.
The pair, aged 56 and 31, would find out the room numbers of Gulf tourists, then go to reception posing as them and saying they had lost their key, according to police.
They would use the stethoscope to listen at the door to ensure nobody was inside and the chisel and hammer to remove the safe from the wall before putting it in a suitcase and leaving
Their career came to an end on 24 August in the central French town of Saint Etienne, where they had stopped on their way back from a visit to Spain.
They were apparently identified thanks to video surveillance of a previous robbery.
Police say they later found 80,000-euros-worth of jewellery, expensive clothing and foreign currency, mostly from Gulf countries, as well as 20 hotel room key cards and the tools that served to perform the robberies.