The king hand-stamped the mark of the king on a cross – believed to be the first time a king has done so in British history.
The hallmarking took place at The Goldsmiths’ Centre, where Charles met apprentices and apprentices in the jewelery and silversmith’s trades.
The silver processional cross, hallmarked by Charles, was commissioned by The Goldsmiths’ Company on behalf of the former Prince of Wales and is a gift from the King to the Church in Wales.
It was created by silversmith and master craftsman Michael Lloyd using traditional silversmith skills which are taught to the young people who met the King during the visit.
Commenting on the hallmarking, Lord Bridges, Chief Warden of Goldsmiths’ Company, said: “We believe, sir, that this is the first time in the history of the country that the king of this country has made the mark of the king.”
Lord Bridges joked he didn’t “want to increase the pressure in any way” as laughter rippled through the room.
Charles had a chance to try out the procedure in two practice runs before hammering the mark onto the cross.
He breathed a sigh of relief when told it was “perfect” – and then jokingly asked Mr Lloyd if he “ruined” it.
The cross was made from sheet silver made from recycled gold bullion – provided by the Royal Mint in Llantrisant – and a shaft of felled Welsh wood.
The part of the hallmark that Charles marked on the cross was the leopard’s head – or king’s mark – which is the city mark for London.
All items sold within the UK containing elements of gold, silver, platinum or palladium must be marked by law, which is regulated by the British Hallmarking Council.
Hallmarking is one of the oldest forms of consumer protection in the UK and the term comes from a mark placed at Goldsmiths’ Hall.
The Goldsmiths’ Center that Charles visited is celebrating its 10th anniversary this year.
It is an educational charity dedicated to enhancing the skills and shaping the careers of jewelers, silversmiths and people working in the precious metals industry.
Presented with a gold-plated pin designed to commemorate the center’s decade, Charles said: “I am very touched.”