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The Trial of the Pyx in the Middle Ages 

The Trial of the Pyx in the Middle Ages

During the Middle Ages, controlling the weight and quality of the king’s coinage was very important. The task of creating gold and silver coins offered lots of opportunities to commit fraud and keep some of the precious metals.

During William the Conqueror’s reign, when the Government received coins as taxation, it simply weighed them to test their value. However, at the time of the recoinage of 1247, evidence suggests that the authorities used what were called ‘trial plates’ to judge the coins’ value. Trial plates were more formally introduced in 1477 and are still used to test coin quality to this day.

Trial plates were sample pieces of precious metal. The Government could check coins against these plates to see if they were of a good enough quality. This testing was known as ‘assaying’ and the process became an annual event known as the Trial of the Pyx.

The Government could also test coins by touchstone, which was the day-to-day practice at The Royal Mint throughout the Middle Ages. As well as the touchstone itself, The Royal Mint kept a set of  ‘touches’ (called ‘needles’) that consisted of 647 pieces of gold of varying alloys. The gold to be tested was streaked across the stone and the mark it made was compared with the needles to ascertain its quality. Although it took an experienced eye to judge the mark, it was an extremely accurate way to check the quality of a coin.

A difficult job

The Master of the Mint had a hard task ensuring the quality of the nation’s coinage. For example, in 1318, when it was discovered that the gold alloy wasn’t up to standard, the Master of the Mint was put in prison.

In 1423 another Master of the Mint claimed that his coins were finer than ever before. The House of Commons took him to task, pointing out that making currency of a better quality than it should be “Would cause it to be broken, melted again, or borne out of this land, for the advantage that may be had therein, for goodness of the alloy.” The Master of the Mint had to tread a very fine line!

Coins in circulation no longer contain any gold or silver but the whole system of currency still relies on the consistency and quality of the coins in circulation. The exact weight and dimensions of our coins are still very important and are independently adjudicated at the Trial of the Pyx each year.


These gold and silver trial plates date from 1477 onwards and are a vital part of The Royal Mint’s history

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