Hallmarking the articles of precious metals

Hallmarking the articles of precious metals at the highest professional level is carried out by the Sector for national and chemical measurements organised at the Metrology Institute of the Republic of Slovenia (MIRS). Suppliers of products made of precious metals are obliged to ensure that the articles comply with the prescribed technical requirements before placing them on the market. The supplier can ensure the conformity of his articles in two ways:

• by submitting articles for hallmarking with a conformity mark in our Assay Office or
• independently by maintaining the prescribed technical documentation.

To determine the fineness of alloys we use following qualitative and quantitative chemical analytical methods:

• platinum: X-ray fluorescence spectrometric method,
• gold: cupellation  SIST EN ISO 11426 (accredited method),  X-ray fluorescence spectrometric method,
• palladium: X-ray fluorescence spectrometric method,
• silver: potentiometric titration  ISO 13756 (accredited method),  X-ray fluorescence spectrometric method.

Our laboratory regularly participates in international comparisons organized by the Convention on Control and Marking of the Articles of Precious Metals (Hallmarking Convention), of which the Republic of Slovenia has been a full member since 2009.

Every year we organize an inter-laboratory comparison for laboratories of suppliers in Slovenia that independently ensure the conformity of their articles and for laboratories of other National Metrology Institutes (NMI), which are responsible for the conformity assessment of the precious metals articles in their country.

Marks on precious metal articles

Precious metals articles must be marked with three markings (supplier mark, fineness mark and conformity mark). All three marks on precious metal articles guarantee the quality of the product to the customer.

Supplier's mark (name stamp)

Each supplier is obliged to mark precious metal articles with his supplier's mark (manufacturer, manufacturer's representative or importer). Based on a filled request, the Metrology Institute issues a decision on the mark of a supplier.  The procedure and form of the supplier's mark are determined in the Rules on the supplier's mark. Each supplier has a unique label by which the customers can identify it.

Fineness mark

The mark of fineness must be engraved on the precious metal article next to the supplier's mark. It consists of a combination of three numbers. The fineness mark certifies that the article conforms to one of the standardised finenesses of precious metal alloys. 

Conformity marks

After marking the articles with the supplier's mark and the fineness mark, the supplier must submit all articles for hallmarking with the mark of conformity. Conformity marks (assay marks) have the shape of a shield bearing the chemical symbol of precious metal, the SI mark and the location number of the Assay Office where precious metal articles have been hallmarked. The conformity mark guarantees the conformity of the articles with the prescribed technical requirements.

The supplier, who ensures the conformity of his articles by maintaining the prescribed technical documentation (self-declarant), confirms the conformity of the precious metal articles with the imprint of the conformity mark in the form of the letter "S".

The conformity mark has to be imprinted next to the supplier's mark and the fineness mark.

Common Control Mark

At the request of a supplier, the Assay Office may additionally mark tested articles with the Common Control Mark - CCM (besides the assay mark). CCM mark indicates that the articles have been controlled at the highest level and enables free sale of precious metal articles on the international market.

Online purchase of articles of precious metals

When purchasing articles of precious metals online, you should make sure that the articles are appropriately marked with three markings (supplier mark, fineness mark and conformity mark). When making a purchase, attention should be paid to the pictorial representations of the conformity marks, i.e. the state stamps and the table of standard fineness grades, which must be prominently displayed on the website or point of sale (paragraph two of Article 23 of the Precious Metal Products Act).

The same applies if the products have been controlled and marked in accordance with the national legislation of another European Union Member State or the Hallmarking Convention (also known as the Precious Metals Convention), in which case it is also necessary to display images of the corresponding conformity marks, i.e. the state stamps or the CCM, in a prominent position on the website or point of sale.