Indeed, such postmarks were used only on the days of their issue corresponding to the dates when the final concerts of the various editions took place.
The originality and the reduced number of postmarks make them a little big treasure, which besides being a source of pleasant curiosity for the audience, interest several collectors worldwide, who will succeed in getting such unique pieces.
The Renata Tebaldi Foundation is the only institution which has and owns such postmarks.
For further information concerning postmark purchase, please write to: info@fondazionerenatatebaldi.org