I always wondered what metal these things are struck on.
There isn't any info on set specifications that I can find on paperwork included with such sets and none to be found online.
Anybody know for sure? Please elaborate.

For example
The silver colored medallion in the
1994 - 1997 Silver Proof Piedfort Pound Four Coin Set
and The gold colored medallion in the
1990 United Kingdom Gold Proof Sovereign Four Coin Collection(I suspect this might be gold plated sterling silver by the way it feels)
