Identify and value Art nouveau box

[Labbayebrocante]

Hi, can someone Identify what the purpose of this box is for, its unusual in the fact that the box sits in the tray base so was it for a small purfume bottle or a small clock.. There is enamel detailing around the lady's head. I believe it to be from the art nouveau period.. But really scratching my head as to its use..many thanks regards Nina [ external image ]