The regulation requiring precious metals sold to consumers must be tested by the authority was started in 1300 by King Edward I of England. Today, after 700 years, when you purchase a UK Hallmark ring from England Diamond, you will find three marks on the inside of the ring: the leopard head ( a symbol in use for 700 years and now represents the assay office in London), England Diamond's sponsor mark (a symbol issued & recognized by the assay office), and the metal fineness symbol ("750" if it is 18K gold). The marks are punched in London by the authority only when the gold purity test is passed. See our UK Hallmark range.