Royal Mint: Trial of the Diets

Royal Mint records relating to quality control of the work of the provincial assay offices known as the 'Trial of the Diets'.

The series consists of fidelity bonds entered into by officials of provincial assay offices 1773 to 1784 and 1854 to 1932. There is also some correspondence and papers dating mainly from the twentieth century.

From 1701, the Mint had a responsibility for quality control of the work of the provincial assay offices which hallmarked all gold and silver items manufactured in England and Wales. Its powers were strengthened by the Plate Assay Act 1772 and the Gold and Silver Plate (Scotland) Act 1836. The assay offices in Edinburgh and Glasgow were brought under Mint supervision in 1927. In a process known as the Trial of the Diets, samples of scrapings (called the diets) taken from the products hallmarked were accumulated by the assay offices and submitted to the Mint once a year for trial by the Queen's Assay Master.

The Royal Mint's responsibilities did not extend to the hallmarking carried out by the London Assay Office which is part of the Goldsmiths' Company. However, under the Hallmarking Act 1973 the trial of the diets was superseded by a system of inspection by the Royal Mint of all assay offices, including the London Assay Office.