South Vietnam, 5 Years Membership in the World Postal Union, January 10th, 1956, Michel Nr. SVN 108-110; Three stamps with nominals of 60c, 90c and 3D were issued in perforation 12.
Here is the mint set
Cancelled specimen are surprisingly hard to find and mint sets outnumber canceled ones by at least 50:1. Here is the postally cancelled set on a piece.
Canceled block of four of the 3D value
These stamps were not officially released imperforate however a small number of imperforate trial proofs have come to market. Here is the imperforate set in pairs.
Here is the entire set in matching bottom margins with a red overprint “Specimen”. The small punch hole was added by the postal authority to ensure that the stamps were invalidated. Rare.
A very small number of Enpreuve de Luxe imperforate sheetlets, also called “Minister Blocks” were produced on light carton paper which had blocks of four imperforate samples of the stamps attached and were handed out or sent to very important people of other countries. These early sheetlets are very rare and seldom come to market. They are not comparable to Enpreuve de Luxe issued later primarily for the benefit of collectors.
First Day Card that features the entire set and was actually processed through the mail. The card was posted in Saigon and sent to France.
First Day Cover featuring the entire set on an international air mail letter sent from Saigon to France. Machine Saigon cancel on front.
Mixed franking featuring the 60c and 90c value paying an overall postage of 1.50D on a rare surface letter sent to France on the first day of issuance.
Mixed franking of two 60c and one 90c UPU Membership stamps together with the 2P Landscape stamp paying an overall postage of 4.10D on an international letter sent from Saigon to France.
Registration Nr. 200130