Hallmarking Precious metals used in jewellery and giftware manufacture are always used as an alloy. The precious metal must be mixed with other elements to give it the necessary properties such as flexibility to produce a desirable and durable article.
Even the most experienced jeweller or chemist cannot tell how much precious metal there is in an alloy, just by looking at it, nor whether a thick plating of gold is covering a base metal interior. Due to the high price of precious metals, this offers a huge opportunity for fraud and there has therefore always been a need to protect the public, and honest suppliers, from those who are tempted to cheat them.
Therefore all items being sold as gold, silver, platinum or palladium in the UK must be hallmarked to confirm that they meet the legal standard. This cannot be done by the manufacturer or importer; goods must be submitted to one of the four UK Assay Offices, or an Assay Office belonging to the International Convention.
The only items which are exempt are those which are under the legal weight threshold:
0.5 grams for Platinum
1 gram for Gold
1 gram for Palladium
7.78 grams for Silver
When an item is received at an Assay office it goes through three processes:
SAMPLING traditional method to remove a tiny piece of the precious metal for testing. Today we are more likely to use a non-destructive method using XRF (X-Ray Fluorescence Spectrometry) machines
ASSAYING to determine whether the precious metal content of the alloy meets the required standard.
HALLMARKING to apply the appropriate mark to the article.