What are some common markings denoting items as real gold?

In the United States, the quality of gold is usually stamped to indicate purity instead of karatage, with fineness expressed in divisions of 24. A 24-karat piece of gold is marked with 999, while an 18-karat piece is marked with 750. Fake gold does not carry such markings.

If a piece is stamped with karatage instead of fineness, it is stamped with a number such as 14k or 18k. The fineness can be determined by dividing the number by 24. The piece itself is not required to be marked, as signage close to the piece of jewellery or verbal information suffices. When an item is marked, it is required to have a trademark stamp near the purity mark to identify its origin.