Understanding Hallmarks. A Guide For Jewellery Sellers

Everything you need to know about jewellery hallmarks before selling

When preparing to sell a piece of jewellery, one of the first things a specialist will check is the hallmark. But what exactly is a hallmark — and why is it so important?

Whether you’re looking to sell antique, vintage, or modern jewellery, understanding hallmarks can give you valuable insight into your item’s origin, metal purity, and potential value.

This guide explains the essentials of hallmarking, so you can feel informed and confident when approaching a valuation or auction.

What Is a Hallmark?

A hallmark is an official stamp or series of marks applied to a piece of jewellery to certify the type and purity of the metal, and in many cases, provide information about where, when, and by whom it was made.

In the UK, hallmarking is a legal requirement for any piece made of precious metals — gold, silver, platinum, or palladium — above a certain weight.

Legal Tip: In the UK, gold items over 1g must be hallmarked to be legally sold as gold. For silver, it’s 7.78g; for platinum, 0.5g; and for palladium, 1g.

What Can a Hallmark Tell You?

A full hallmark typically includes four key components:

1. Metal Fineness Mark

   • Tells you the purity of the metal (e.g., 750 = 18ct gold, 925 = sterling silver)

2. Assay Office Mark

   • Indicates where the item was tested and hallmarked

   • UK options include London (leopard’s head), Birmingham (anchor), Sheffield (rose), and Edinburgh (castle)

3. Sponsor’s Mark

   • The unique initials or symbol of the maker or company responsible for sending the item for hallmarking

4. Date Letter (on older pieces)

   • A letter that corresponds to a specific year — particularly useful for dating vintage and antique jewellery

🔍 Example: An 18ct gold ring with a leopard’s head, “750”, and a maker’s mark of “CR” was likely hallmarked in London and made by a jeweller with those initials.

Why Hallmarks Matter When Selling Jewellery

1. Authenticity & Trust Hallmarks provide a guarantee of metal quality, helping you build trust with buyers, especially at auction.

2. Accurate Valuation A qualified valuer will use hallmarks to confirm the metal content — a crucial element in pricing your piece correctly.

3. Dating the Piece For antique or vintage jewellery, hallmarks help establish the age, which can dramatically impact value and collectability.

4. Identifying Makers Famous or desirable makers (e.g., British court jewellers, Art Deco ateliers) can add significant premium — hallmarks are the key to unlocking this.

Common Hallmark Confusions

• Not all marks are hallmarks: Stamps like "Italy" or "925" on their own do not constitute a full UK hallmark.

• Foreign marks differ: Continental jewellery may carry different systems or symbols — our experts can interpret these for you.

• Some antique pieces may be unmarked: Pre-20th century items were not always hallmarked, but they can still hold substantial value — so don’t dismiss them!

  
  

Can You Hallmark Jewellery After It’s Made?

Yes — if you have an item that is unmarked but believed to be gold, silver, or platinum, it can be tested and hallmarked retrospectively at a UK Assay Office. This is particularly useful when preparing items for auction or sale.

At Furlong, we work with trusted partners to ensure proper testing and hallmarking where needed.

Expert Tip from Furlong

“Understanding hallmarks isn’t just about metal content — it’s about telling the full story of a piece. From provenance to purity, these tiny marks carry huge weight.”– Charlotte Rose, Head of Jewellery, Furlong Auction House

Ready to Find Out What Your Jewellery Is Worth?

If you’re thinking of selling jewellery — whether it’s hallmarked or not — our specialists can help.

We offer free, no-obligation valuations, with expert guidance on everything from hallmarks to hammer prices. Book a private appointment at one of our offices, or start with a virtual valuation.

Book Your Free Jewellery Valuation