The Cognac appellation is divided into six crus delimited since 1909, arranged concentrically around the town of Cognac. Each cru possesses its own geological identity that shapes the character of the eaux-de-vie. Grande Champagne, the premier cru, lies on chalky soils rich in Campanian limestone and produces the finest eaux-de-vie with exceptional aging potential. Petite Champagne shares this calcareous signature with a slightly more accessible structure. Borderies, the smallest cru of the appellation, offers clay-limestone soils enriched with flint, yielding floral and rounded eaux-de-vie. Fins Bois, extensive and generous, presents varied clay-limestone and sandy terroirs producing fruity and supple cognacs. Bons Bois and Bois Ordinaires, more peripheral and influenced by the oceanic climate, develop more rustic and maritime profiles.

Vallein Tercinier crafts its cognacs from parcels located in Grande Champagne, Petite Champagne, Fins Bois, Bons Bois, and Borderies. Cognacs are produced by distilling wine made primarily from the Ugni Blanc grape variety, which accounts for over 95% of regional production. The house works traditionally with historic copper alembic stills, following the classic Charentais method of double distillation. After pressing, the juice ferments for two to three weeks, resulting in a wine with 7 to 8% alcohol content. Distillation occurs in traditional Charentais copper alembics, producing a colourless spirit at approximately 70% alcohol. The eaux-de-vie are then aged in Limousin oak casks for a minimum of two years.