What does does G23 on the back of a gold piece mean?

The "G23" marking on the back of a gold piece typically indicates the purity of the gold, specifically that it is 23 karats, which translates to approximately 95.83% gold content. In the context of jewelry or coins, this mark helps consumers identify the quality of the gold. Additionally, it may also signify the manufacturer's or designer's mark, providing information about the origin of the piece.