Vacheron & Constantin early 1970's buckle markings:
AW is the maker's mark, a well known manufacturer of buckles.
SWISS is origin.
0,750 is 18K gold.
Déposé is shorthand for Modèle Déposé, which is Swiss/French for "Registered Design".
I could not make a gold test... but at least, it looks authentic.
Below two buckles of this area, left: ref 2019, right: ref 602 or 35202 'Prestige de la France' from early 1970's.
On the top of the satinised surface (corresponding to the satinised surface of the watch) of the left buckle appears nothing, maybe refinish.
