Poinçon French Eagle's Head Hallmark Indicating a Minimum Fineness of 18k Gold, Made in France, est. 1838. (Plus Obscured Dog's Head for Platinum.) Poinçon is French for the mark on metal indicating its fineness. Another term for hallmark. (The mark in the diamond-shaped cartouche is a French Maker’s Mark.) Related Reading Hallmarks on Period Jewelry