By UK Law (The Hallmarking Act of 1973) all jewellery sold in the UK must obtain a hallmark. Over the years, the marks have been altered, adapted and evolved but it is still a legal requirement to have: an Assay Office mark, Standard mark and Sponsors mark. Any other marks are optional. Any items that can be proven to be manufactured before 1950 are exempt.
Sponsors Mark: initials of the person or company who are presenting the piece to be hallmarked. Although it often can be, it is not always the "manufacturer" of the jewel. The "sponsor" accepts complete responsibility for the article.
Makers Mark: The ‘manufacturer’ of a piece. More prevalent pre 1720 as it then became the norm to use initials, rather than the then used monograms or symbols.
Date Mark: Used to help establish the year of manufacture. This can also just be the year the jewel was hallmarked. Since 1999 it has not been obligatory to use a date mark.
Standard Mark: Carat stamp (375/585/750/916/925/950 etc)
Import Mark: Used between 1904 and 1998. What was considered a useful mark by many, the import mark still showed which hallmarking office the jewel had been stamp in, but the city mark was different to it's usual mark which was proof it had been imported outside of the UK.
Control Mark: Known as the ‘convention mark’. Brought in to control the standard of gold coming in to the UK from abroad. A ‘minimum’ control mark is used to stamp the item whilst in a pre-finished condition. It can then be hallmarked to a UK standard.
Assay Office Mark: Today there are only 4 Assay Offices left in the UK: Birmingham, London, Sheffield, and Edinburgh.
Each an individual business, but part of the “British Hallmarking Council”, Birmingham is the largest and busiest Assay Office in the world. Having moved premises only 3 times in its long history, 2015 has seen them move to a purpose built modern building to continue their sterling work in conjunction with not only the Jewellery Quarter, but the rest of the jewellers in the UK.
In times gone by, there were also offices in: Chester, Dublin, Exeter, Glasgow, Newcastle and York.
Special Marks: Most recent marks are the Millennium Mark (2000), Queen’s Golden Jubilee (2002) and Queen’s Diamond Jubilee (2012). Other occasionally seen marks are Queen Elizabeth II’s Coronation Mark (1953) and Queen’s Jubilee (1977).