Dior Dioressence was originally created and released by Guy Robert in 1969.  In 1979  by Dior decided to reissue Dioressence. I can find no information on why it was reformulated but reviews say that the pungency of the ambergris in the 1979 version has been substantially reduced. It is not actually even listed as a note in the fragrance. This new version was created by Max Gavarry and while it followed the general outlines of the original Dioressence, it was made sweeter and spicier. Most vintage Dioressence that is around today is this version and it is very beautiful, just not as animalic as the 1969 version. Supposedly Dior's in-house perfumer, Francois Demachy, admitted in an interview that he disliked the current version of the fragrance and in 2010, the newest version of Dioressence was launched in the Creations de Monsieur Dior lines.

This is the 1979 Gavarry eau de toilette version of the fragrance.