There’s a Guerlain flacon montre on the shelves in the bedroom of Lallo di San Marciano (Pierre Clémenti). In the film the disk on the bottle is dark; we can make a few assumptions [1], but still it’s impossible to say what cologne it contained. I’d like to think it was Mitsouko.
[1] It could be Ode (purple disk), Vol de Nuit (navy blue disk), Jicky (burgundy disk) or Liu (black disk).
World Wide Aura 
