Borre style brooches of this type, Petersen P51, were found at Birka Sweden, Norway and Denmark and were popular during the 9th and 10th centuries. These brooches are lighter and airier than the than the artifact brooches and allow the color of the garment to show through the piercings. They are 3 1/4" x 1 7/8" or 80mm x 48mm. The original brooches were made in two parts. The base had a domed center that was soldered to the decorative pierce work top to create a shadow box effect.