Very attractive georgian locket/brooch with a slightly domed glass centre and two rows of old cut and rose cut diamonds in closed back pinched collet silver settings.  
The reverse of the locket is gold, with a removable glass back. (no hinge, has to be prised open) 
The locket i'm sure, used to contain hair but is now empty an your own memento can be added, be it a painting, or a lock of hair from a beloved pet.
 
The is a brooch pin to the reverse, which can be removed.
 
The piece measures 35mm x 29mm
 
weighs - 13.3g
 
In good antique condition. 
 
English circa 1800