What is 375 hallmark?

The 375 hallmark indicates that a piece of gold jewelry is made of 9 carat gold, which contains 37.5% pure gold and 62.5% other metals, such as copper or silver. This hallmark is commonly used in the UK and some other countries to signify the gold content of a piece. The number "375" is stamped on the item to assure buyers of its gold purity.