What is a Hallmark?

Your Guarantee of Purity

All diamond pieces on the Diamondsmith website are made in either Platinum 950 or 18k Gold; they are sent to hallmarked in the Assay Office in London before sending it out to customers. All our precious metal products comply with the Hallmarking Act, so you can be confident that what you buy from Diamondsmith is ‘real’ and as described. Unfortunately, many overseas websites are not bound by UK law and do not offer the same guarantee that the items they sell are genuine.

Dealer’s Notice

Under the Hallmarking Act 1973 all dealers supplying precious metal items must display a notice explaining the approved hallmarks. This must be in the form produced by the British Hallmarking Council.

The Full Traditional Hallmark comprises five marks:

  • Sponsor’s mark 
  • Traditional fineness mark
  • Millesimal fineness mark
  • Assay Office mark
  • Date letter mark

Protecting Jewellery Shoppers

All items (over certain weights) sold in the UK and described as being made from gold, silver, platinum or palladium must have a legally recognised hallmark. The law is set out in the Hallmarking Act 1973 (which has been amended and updated on various occasions).

Finenesses recognised under the Convention are:

The purpose of hallmarking is to protect buyers of precious metal items against fraud. The hallmark is a mark which shows that the item has been independently tested and verified as matching its description, and conforming to all legal standards of purity or fineness of the metal.


It is not possible to detect by sight or by touch the gold, silver, platinum or palladium content of an item. It is therefore a legal requirement to hallmark all articles consisting of silver, palladium, gold or platinum (subject to certain exemptions) if they are to be described as such.

Precious metals, such as gold, silver, platinum and palladium, are rarely used in their purest form. They are mixed with other metals to form an alloy that has the desired colour and strength. It is very difficult to know what an item of jewellery is made of just by looking at it or touching it. Hallmarking protects consumers by certifying the precious metal content of the piece so that the buyer knows that the item is genuinely what the seller says it is.

Online selling of jewellery increases the risk to consumers, but the hallmark gives the buyer confidence that the products are genuinely what they say they are.

If a precious metal item weighs less than a certain amount it is not compulsory to apply a hallmark. The minimum weight thresholds are:

  • gold 1 gram
  • silver 7.78 grams
  • platinum 0.5 gram
  • palladium 1 gram
Platinum, gold, palladium and silver are the only four metals that can be hallmarked in the UK. These hallmarks indicate the metal, its purity percentage and where and when it was hallmarked.
All Jewellery sells on Diamondsmith will be hallmarked in the Assay Office before sending it out to customers.

Hallmarking Act 1973

Hallmarking: practical guidance

For more information, please visit www.edinburghassayoffice.co.uk or the Assay Assured website: www.assayassured.co.uk.

Start typing and press Enter to search

Shopping Cart
No products in the cart.