The process of hallmarking is adding a mark to the item which shows that it has been independently tested and verified as matching its description, and conforming to all legal standards of purity or fineness of the metal. Sterling Silver is legally required to be hallmarked if the item weighs over 7.78 grams. Most items under this weight will not have a hallmark as the item may be too small or the mark would detract from the design. In most cases, your jewellery will be marked with a 925 stamp.