Gold Assay & Hallmarking
Once assayed by fire, now tested by X-ray Fluorescence. Find out how we verify and hallmark gold here at Birmingham Assay Office.
Gold Assay & Hallmarking in the UK
Gold is one of the world’s most recognised and sought-after precious metals, valued for its beauty and rarity. Used in jewellery, watches, investment products, and luxury goods, gold is available in a variety of purities and colours. To ensure that gold items are accurately described and meet legal standards, they must be independently tested and verified through the assay and hallmarking process. Hallmarking provides assurance that a gold item contains the precious metal content claimed by its manufacturer or retailer.
What Is Gold Assay?
Assaying is the process of testing a precious metal item to determine its purity. Before a gold item can be hallmarked, it must be independently examined by an authorised UK Assay Office to confirm that it meets the required legal standard.
During the assay process, Birmingham Assay Office specialists analyse the metal content using X-ray fluorescence (XRF) to verify the proportion of pure gold present in the alloy. Only items that meet the required standard are eligible to receive a hallmark.
How to Identify UK Gold Hallmarks
Gold hallmarks are marks applied to precious metal items to confirm their purity and provide information about where and when they were assayed. Understanding these marks can help you verify the authenticity, age, and origin of your gold jewellery and collectable pieces.
What Is a UK Gold Hallmark?
A UK hallmark is a series of symbols stamped onto an item made from precious metal. Hallmarking is a legal requirement in the UK for gold items weighing 1 gram and over, and provides assurance that the metal meets the required standards of fineness
A traditional UK gold hallmark typically contains several key marks:
The Sponsor’s Mark
(Previously known as a Maker’s Mark)
The Fineness Mark
750, 75% Gold
The Assay Office Mark
Birmingham Assay Office
Step 1: Identify the Gold Purity Mark
The fineness mark indicates the purity of the gold. The number represents the parts of pure palladium per thousand.
For example, a hallmark reading “950” confirms the alloy is 950 parts palladium and 50 parts other elements, containing 95% pure palladium. This is the most common fineness for palladium jewellery.
Common UK gold standards include:
375 or 9ct Gold, 37.5% Gold
585 or 14ct Gold, 58.5% Gold
750 or 18ct Gold, 75% Gold
916 or 22ct Gold, 91.6% Gold
990, 99% Gold
999, 99.9% Gold
Step 2: Look for the Assay Office Mark
Every hallmarked Gold item is tested and certified by an authorised UK Assay Office. The assay office mark shows where the item was independently tested and hallmarked.
Each office has its own unique symbol:
Birmingham Assay Office
London Assay Office
Sheffield Assay Office
Edinburgh Assay Office
Step 3: Find the Sponsor's Mark
The sponsor’s mark (sometimes called the maker’s mark) identifies the company or individual who submitted the item for hallmarking.
This mark usually consists of two to four initials within a shaped shield.
Sponsor’s Mark: Birmingham Assay Office
Step 4: Check the Date Letter (If Present)
Many older British gold items feature a date letter. This alphabetical mark changes each year and can help determine when an item was hallmarked. The date letter was a compulsory hallmark until 1999.
Date letter styles vary between assay offices and different hallmarking periods, so a specialist date letter chart is usually required for accurate identification. You can find ours here.
Date Letter 2026: Letter B
No Purity Mark? Look for a Traditional Fineness Mark
Before the introduction of the modern numerical fineness marks used today, British gold was identified using the crown, a symbolic standard mark. This traditional mark remains important for collectors, dealers, and anyone researching antique gold.
Fineness Mark: Gold
Convention Marks
The Convention Mark is an optional hallmark that indicates a precious metal item complies with the standards of the International Hallmarking Convention, also known as the Vienna Convention. Introduced in 1972, the Convention enables hallmarked items to be more easily recognised and traded between member countries without the need for re-testing or re-hallmarking.
On gold items, the Convention Mark takes the form of a set of scales either containing the fineness number or alongside the fineness mark. When present alongside UK hallmarks, the Convention Mark provides additional assurance that the item meets internationally recognised standards of purity and has been independently tested by an authorised assay office.
Common Control Mark Type 1: 750 Gold
Common Control Mark Type 2
Common Misconceptions About Gold Marks
A Crown Doesn’t Always Mean Gold
Sheffield Assay Office did not begin hallmarking gold until 1903. At that time, its assay office mark was a crown, as was the traditional gold standard mark. Although both marks featured a crown design, they were distinct hallmarks serving different purposes and can be differentiated by their shape and context within the hallmark.
To avoid confusion, in 1904 Sheffield Assay Office adopted the Yorkshire rose as its assay office mark for gold, while continuing to use the crown as its assay office mark for silver. Following the Hallmarking Act 1973, Sheffield Assay Office replaced the crown with the Yorkshire rose for all precious metals in 1975.
As a result, it is possible to find an antique silver item hallmarked in Sheffield bearing a crown, as this was the Sheffield Assay Office symbol for silver until 1975.
What’s Your Treasure Worth?
Here at Birmingham Assay Office, we offer valuations of watches, jewellery and silverware, whether you need them for insurance replacement, probate, family division, private sale or other official purposes. Our expert valuers are experienced and trusted to deliver accurate, detailed valuation reports that are widely recognised by insurers, legal professionals and the trade.