Digard will be selling the collection from their home at Autheuil, situated 55 miles from Paris, at Drouot on June 26.
The sale will include paintings, furnishings and many more personal items. They include the piano used by Montand (who was a singer as well as a movie actor), film scripts and their photographic collection.
There is also correspondence from friends and acquaintances including John F Kennedy and Martin Luther King and unpublished letters between Montand and his mentor Edith Piaf.
Pictured here is an Art Deco watch with a diamond set bracelet belonging to Signoret which is estimated at €8000-12,000.