As you can see the exhibited rings are all gold, but at the time they were also made in other metals like silver. The national museum usually only show the most impressive ones.
I especially adore the engagementrings:
The rings from the early part of the Middle Ages are often twined or plaited and occurs from 1050-1150. Twined arm and neck rings were known by the vikings, but the finger rings arrived with the start of medieval times:
Lastly there's the rings inscribed with patterns, intitals or words from the bible. They were popular in the 14th and 15th century.