Read a label
The label on a bottle of Cognac should accurately reflect the origin and the age of the youngest eau-de-vie used in its blend.
Generally speaking, Cognac Master Blenders use eaux-de-vie that are much older than the minimum requirement for their blends. In fact, the most prestigious designations may have aged for dozens of years in oak casks before being presented to the public.
See the animation (in French) « how to read a label »
( Bureau National Interprofessionnel du Cognac)
Learn more : Understanding a Cognac label (pdf from BNIC)