A hallmark is a legal requirement for any item described or sold as precious metal unless it is very lightweight. This applies whether you are buying online or from a shop or any other face to face situation such as a market.

The metals used in making fine jewellery are gold, silver, platinum and palladium. None of these metals are used in their pure form as they do not have the appropriate properties to create jewellery items which will retain their shape and beauty during wear. For this reason they are alloyed with less valuable base metals such as copper, zinc which produces a material suitable for making jewellery.

The amount of precious metal in the jewellery alloy is called its fineness. This makes a significant difference to the cost of the materials and therefore the value of the item. The hallmark confirms that the proportion of gold, silver, platinum or palladium in the piece meets a recognised standard.  It also shows where the item was assayed (tested) to confirm its fineness and who submitted it for hallmarking. The hallmark is a vital, compulsory piece of information giving you independent reassurance that your jewellery or silverware purchase has the right amount of precious metal in it. 

The purity or fineness of gold is measured by assaying. Traditionally this means weighing the gold alloy and then using a cupellation furnace to remove the alloying metals and any impurities, allowing the final pure gold residue to be weighed and compared with the weight of the original alloy and the fineness can then be calculated. Increasingly, new technology is replacing cupellation but this remains the reference test. For example, the fineness of gold can be expressed in carats. Pure unalloyed gold is 24 carats, so 9ct gold is 9 parts gold in 24 or 37.5% pure. Nowadays fineness is expressed in parts per thousand so in the example of gold, 9ct is 375, 14ct is 585. 18ct is 750 and 22ct is 916.

All businesses selling fine jewellery should be displaying the “Dealers Notice” explaining what the hallmark means. This applies to all businesses describing fine jewellery for sale in the UK including online, shops, TV channels, catalogues and any other media.