By law, all precious metals over certain weights must be verified by the assay office. This is your guarantee that the metal you are buying is what you were told you were buying. Sterling silver is silver mixed with an alloy to make it stronger and easier to work with. The ratio is 92.5% silver and 7.5% other metal (usually copper). You cannot tell by looking at a metal whether it is sterling or another combination of alloys. That's where the assay office comes in. There are four assay offices in Britain, London, Sheffield, Birmingham and Edinburgh. I am registered with the London Assay Office to hallmark. Please take a look at the dealer's notice in the photo. All jewellers selling metal over the required weight MUST hallmark the items by law. As a consumer, you have the right to ask to see the dealer's notice when buying any jewellery over the weight requirements and all such pieces must be hallmarked. I am very proud of my hallmark and display the dealer's notice at all markets and fairs.