1920’s French Enamel hotsell Guilloche Secret Locket Brooch

Beautiful metal & enamel Guilloche brooch with a hidden locket in the back.
Marked on the back of the bar with patent number 206696.
Condition is antique, very good. Minor signs of age, wonderful working order.
Measurements are 3 1/4” long, the entire locket itself is 1 5/8” x 1 3/4”.