South Vietnam, World Day of Meteorology, March 23rd, 1963, Michel Nr. SVN 312-315; Four stamps in nominals of 50c, 1D, 1.50D and 10D were issued in perforation 13.
Here is the mint set.
and here the postally used set.
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 matching top margin stamps.
Color Trials; prior to authorizing the final printing run for stamps the Vietnamese Postal Authority requested a few sheets of color sheets on one particular value of a set in order to decide which final color combination would be best suited for each stamp within the set. The color sheets had the size of a standard sheet but contained alternating color options on the designated nominal value. While these sheets were only intended for internal postal use some of them came to market. Virtually all of these complete sheets were cut apart. So one mostly finds single color proofs or small strips of them. While they are actually very rare one can still obtain them for under $10 a piece (with some exceptions) as not many collectors appear to have an interest in them so far. Here are various color trials for the 0.50D value.
Rare multiple franking of the 50c value (2) paying a total of 1D postage on a printed matter mailing from Saigon to Canada in May of 1964.
Mixed franking of the 50c World Day of Meteorology stamps (4) together with the 1.50D Nuclear Energy for Peace stamp paying an overall postage of 3.50D on a domestic letter front sent to Kotum.
Mixed franking of the 50c World Day of Meteorology stamp together with the 1D Birthday of Ngô Đình Diệm paying an overall postage of 1.50D on what must have been a printed matter mailing (the envelope was left open) to West Germany.
Mixed franking of the 1D Dam stamp together with stamps from the Boy Scouts, World Day Meteorology and Atomic Power sets paying an overall postage of 44.50D on a registered international air mail letter sent from Saigon the United States n November of 1964.
Single franking of the 1.50D value on a domestic letter sent by a civilian to a member of the military (KBC 3027) from Nha Trang. KBC 3027 was also thought of being located in Nha Trang. Members of the military only had to pay half the standard postage rate.
Mixed franking of the 1.50D World Day of Meteorology stamps (2) together with two 3D Red Cross stamps paying an overall postage of 9D on an international and sent from Gia Dinh to France.
Mixed franking of the 50c 1.Anniversary of the Revolt against Ngô Đình Diệm stamps (3) together with the 1.50DWorld Day of Meteorology stamp paying an overall postage of 3D on a domestic letter sent within Saigon in November of 1964.
Mixed franking of the 10D World Day of Meteorology stamp together with the 3D Human Right stamp paying an overall postage of 13D on an international air mail letter sent from Saigon to the United States in December of 1964.
Registration Nr. 200460