Hallmarking the Olympic Medals
The 4,700 gold, silver and bronze medals for the London 2012 Olympic and Paralympic Games were produced by The Royal Mint in Llantrisant, South Wales, but the assaying and hallmarking of the gold and silver medals came under the responsibility of the London Assay Office.
Gold Olympic medals have not been made from solid gold since the 1912 Olympics, but measuring 85mm in diameter, the London 2012 Medals were the largest and heaviest ever made for a Summer Olympic Games.
There were 22 stages involved in making the medals — including hallmarking — with each one taking about ten hours to produce. The gold medal is hallmarked as .925 silver, and contains a small amount of gold and copper within each medal. It is then plated to guarantee a minimum of 6g of gold, as per the International Olympic Committee’s specification. The silver medal is also hallmarked .925 silver with the remainder of medal made up with copper. The bronze medal is 97% copper, 2.5% zinc and 0.5% tin.
The Superintendent Assayer at the London Assay Office, John Love, was the only non-Royal Mint employee to be involved in the Olympic medal-making process, diligently hallmarking the medals over the course of eleven visits to Wales.
A short video of the Olympic medal being hallmarked can be see here: http://vimeo.com/42693982 Password: hallmark
Trev.