Hallmark Requirements

Hallmarking weights
The thresholds are 1 gram for gold, 7.78 grams for silver and 0.5 grams for platinum. If you sell an item of gold that weighs more than 1 gram, or an item of sterling silver that weighs more than 7.78 grams, or an item of platinum that weighs more than 0.5 grams, the piece by law MUST be hallmarked.