The ring brooch was the most important piece of jewellery in Norwegian traditional dress. Ring brooches can be circular or heart-shaped, and their design dates from the Middle Ages. They differ from modern brooches in the way they fasten. The wearer pulls the cloth of the garment through the central hole, and then spears it with the pin. The greater the strain on the pin, the more secure the fastening. Ring brooches were worn throughout Norway in the 18th and 19th century. Their shape and pattern varied by district and use. They were worn by men, women, and children.

There are well over 50 different names for ring brooches in Norwegian. Each kind of brooch has its own distinctive name, some of which date back to the Middle Ages.

A slangesølje is a flat brooch with six openwork crescents surrounding the central hole. It probably developed from the rosesølje, and is found in the same region centred on Telemark. It is called slangesølje because the central loops, covered with filigree rings, look like the coils of a snake. They are usually made of cast silver, imitating filigree, or of real filigree on a cast back plate.

This brooch is marked on the back with the maker's mark TG, and the standard mark 13 ¼. TG is the mark of Tor Grinderud, who was a silversmith specialising in traditional jewellery. He worked in Lunde in Telemark from 1825 to 1870. 13 ¼ stands for 828 standard silver, and was used in Norway before around 1880. This brooch was bought for £1 5s. at the International Exhibition, London, 1872.