What does it mean if 750 is stamped on a necklace chain clasp?

If "750" is stamped on a necklace chain clasp, it indicates that the metal is 18-karat gold, which means it contains 75% pure gold and 25% other metals. This quality stamp is commonly used in jewelry to signify the gold's fineness and authenticity. The higher the karat number, the more pure gold is present in the alloy.