Hallmarking gold jewellery in Europe dates back to King Louis IX of France and Edward I of England in the 1200s. As craft guilds developed in the Middle Ages in Europe, state-appointed assayers examined precious metal goods for purity and content. (see Wade’s blog at https://fonya.co,.au/blogs/blog/gold-purity-explained). 

Assayers assigned marks for authentication, the goldsmith who made the piece (gold and silver) and the production date/location. King Edward III of England issued a charter to the ‘Worshipful Company of Goldsmiths’ In 1327. Their headquarters in London was at Goldsmiths' Hall – hence the English term ‘hallmark’ originates with this hall and its official assay marks. These hallmarks have been applied to all precious metals

In the UK, all gold products sold within their shores must be hallmarked at one of the four assay offices in London, Birmingham, Sheffield and Edinburgh each of which has a distinctive mark. Articles weighing less than 1 gram are exempt.

Similar systems to clearly identify the caratage and origin of gold items have been introduced around the world. Each country has created its own requirements and distinctive gold hallmarks. In some countries, including in Italy, India and China, jewellery hallmarking is voluntary. 

The Vienna Convention on the control of the fineness and the hallmarking of precious metal objects (https://www.hallmarkingconvention.org/) was forged by European nations in 1972. Most European nations are party to this. This convention introduced the Common Control Mark (CCM). Each member country agrees to allow goods marked with the CCM mark to be imported without further testing or marking if such articles would normally qualify for a domestic mark. To be marked with the CCM a precious metal must bear a fineness mark, a responsibility mark and an Assay office mark. The CCM thus represents an additional protection and quality mark.

The objective of the Hallmarking Convention (also known as "Precious Metals Convention") is to not only facilitate trade in precious metal articles but to also  maintain fair trade and consumer protection in light of the particular nature of these articles.

So interesting to reflect on the origins of a word that conveys authenticity, purity, guarantee and promise!