Trial of the Pyx

Since 1282, our coins have been measured against the world's most exacting standards in the Trial of the Pyx.

The Trial of the Pyx is an examination by a jury entirely independent of the Royal Mint to ascertain that the gold, silver and cupro-nickel coins made by the Royal Mint are of the proper weight, diameter and composition by law. It is convened annually by an order of council and carried out by the Goldsmiths Company of the City of London. The jury consists of Freemen of the Goldsmiths Company and is presided over by the Queen's Remembrancer who swears in the jury in accordance with directions issued by the Treasury.

For the Purpose of the Trial a number of coins specified in the appropriate Trial of the Pyx Act is produced by the Officers of the Mint and placed in the Pyx, or box. Officers of the National Weights and Measures Laboratory of the Department of Trade produce the standard trial plates of gold, silver, copper and nickel and the weights for use in the Trial.

The jurymen first check the number and denomination of the coins to see that the proper number has been produced, and then weigh the coins in bulk, as well as selected specimens, to ascertain that the average weight of the coins is within the remedy or tolerance allowed by law. They then carry out assays to test accurately the fineness or composition of the metal by comparison with the standard trial plates, and to ensure that it is within the prescribed tolerance. They also measure the diameters of selected coins to ascertain whether they are within the tolerances allowed in the relevant Coinage Acts.

The verdict of the Jury is delivered to the Queen's Remembrancer in May in the presence of the Master of the Mint, or his Deputy.