This is a well known photo of Django playing a Rio guitar in 1948 but it is not generally known that is was taken at the Nice Opera House as part of the first Nice Jazz Festival:-
Behind him is Challain Ferret and you can just see Emmanuel Soudieux's right hand. Joseph Reinhardt is behind and to the right and Stephane Grappelli is standing left. This guitar was probably Marcel Bianchi's and Sarane Ferret also owned one. They were made by the German luthier Karl Schneider and were possibly the first electric guitars produced in Europe.
Here are the poor quality recordings of the group made at this concert and you can hear what the Rio guitar sounded like when played by Django.