These art deco sterling silver and marcasite personalised brooches were very popular during the 1930s. The customer would choose a frame from a wide selection and her initials. The jeweller would then finish the brooch.
In this case the initials are "LAB". The brooch is 1-1/4" square. Marked on the back "Sterling" and "Patented" "This Side Up" on the edge of the frame where the initials are inserted.
Lovely quality and iconic of the era, the brooch is in excellent condition with the pin back in perfect working order.