Most of our knowledge of Viking Age jewelry comes graves and hoards. Because accompanied burials ceased after the conversion to Christianity, we know more about earlier Viking Period jewelry than we do of the later Viking era.
Viking age jewelry tends to be dated according to the art style that is used for decoration.
Jewelry was worn by both men and women. It was a means of fastening cloaks, belts and dresses, And it was an adornment and a means of displaying visible wealth, even as a means of carrying wealth. It could be used as a means of exchange, and as a means of cementing an alliance.
Gold was used for the most prestigious jewelry, but gold was relatively scare in Scandinavia, so most jewelry was made of silver or gilded bronze. Gold and silver items would have been individually made, but bronze jewelry would have been mass produced, using clay moulds from a single master prototype.
In addition to brooches and buckles, silver neck and arm rings were common items of jewelry. Many were made from melted down silver Arabic coins, and were made to standard weights so that their value was easily assessed.
”Silver arm-rings were by far the commonest products of the Hiberno-Viking tradition…Over one hundred are known from silver hoards in Ireland, where they were sometimes cut into fragments which could later melted down and recycled. Several different types have been identified, the most important in terms of sheer numbers being the broad-band type. Like the neck-rings, they seem to have been manufactured for the storage and circulation of silver, and their target weight of 26.15 grams (0.92 ounces) is very close to the most important weight unit of the lead scale-weights from tenth-century Dublin. Their purity was obviously a matter of concern, because they sometimes display small nicks and pecks.”
Source: Netherton, R. and Owen Crocker, G. R. (eds) (2006), “Medieval Clothing and Textiles vol 2″