Your item will be sent to Assay Office for Hallmark Assessment. This is a legal requirement in the UK to ensure the purity of gold of the item meets the legal standard.
In other words, if an object is stamped with a ‘gold’ hallmark, then you, the consumer, knowing that it is indeed real gold – and not something else that simply looks like gold.
For 18k Gold Jewellery, item will be marked as 750. For Platinum 950 Jewellery, item will be marked as 950.