14K gold brooch made from an originally so called: Oorijzer

This Oorijzer (a Dutch name for literally an ear iron) belongs at the head coverings of old Dutch costumes. Originally a type of iron head-dress worn as peasant jewelry by the woman of Friesland (a region in the North-West of Holland). Later adapted as a gold helmet (see picture 4) fitting tightly over the head and worn under a lace cap(see picture 3). It has a cleft opening extending from the brow to the crown, derived from the 17th century iron type, and is made with rosettes at the side that hide pins which secure it at the temples to the lace cap.
This 14K yellow gold brooch was made of one of such a beautiful rosette. Hallmarked with an Oak leaf (1852-1906). The measurements of the brooch are: 5 cm (2") - 5,8 cm (2.2"). On the picture you can see an example of this kind of peasant head-dress costume.