Berlin iron is a black-lacquered cast iron material used in jewelry making beginning c. 1790. Originating in Silesia, Prussia at the Gleiwitz Foundry, the Royal Berlin Foundry and a manufacturer in Horovice, Bohemia all produced jewelry in this manner. The French subsequently followed suit, Fer de Berlin, after Napoleon absconded with the casting molds on his march on Berlin.

The process involved molding wax which was then pressed in sand creating impressions into which molten iron was poured. The hand-finished pieces were then coated with black lacquer. Early Berlin ironwork was typically neo-classical in design and included cameos and classical figures. The style changed to more naturalistic designs c. 1815, followed by Gothic Revival styling c.1825.

Most ironwork is unsigned.  A few signatures of note are Geiss, Lehmann, Hossaur, and Devaranne. Similar steel mesh jewelry was also produced in Woodstock, England. These items are usually decorated with small steel flowers, sequins, stars and the like.