10 francs Montesquieu épreuve de contrôle

Épreuves de contrôle are internal checking pieces struck by the Monnaie de Paris to verify die alignment, depth, and overall quality before authorizing full production runs — they were never intended for circulation or public sale. Lead's malleability makes it ideal for this purpose, capturing fine detail without the hardness that can mask subtle die faults. The 1989 Montesquieu issue commemorated the bicentennial of the French Revolution, a series that generated considerable institutional interest and correspondingly careful quality oversight.