Poinçon

Poinçon is French for the mark on metal indicating its fineness. Another term for hallmark.
French Eagle's Head Hallmark Indicating a Minimum Fineness of 18k Gold, Made in France, est. 1838. (Plus Obscured Dog's Head for Platinum.)

French Eagle’s Head Poinçon Indicating a Minimum Fineness of 18k Gold, Made in France, est. 1838. (Plus Obscured Dog’s Head for Platinum.)