Berlin iron brooch "Queen Luise of Prussia" Bust portrait of Luise of Mecklenburg-Strelitz, wife of the Prussian king, with tiara and pearl necklace. Weight approx. 11.48 g. The "Gold I gave for iron" campaign was used to finance the battle in Prussia (18th/19th century) against Napoleon and his troops. In exchange for their jewels, the donors received jewellery made of cast iron, the "Berlin iron". Iron brooch with a portrait of Queen Louise of Prussia.