Meet the guardians of gold

Analysts at Goldsmiths’ assay office in London, UK, are responsible for testing all the country’s coinage in a centuries-old ritual called the Trial of the Pyx. It takes them two to three months to test the 50,000 coins supplied by the Royal Mint. They also hallmark precious metals used in jewellery and test alloys to see how much gold or silver is present. The analysts use x-ray fluorescence spectroscopy, fire assay cupellation, potentiometric titration and inductively coupled plasma emission spectroscopy.