Auction # 2027 ARGENTINA: Special July auction

GJ.1626, 1974/6 30c. Belgrano PRINTED IN NEGATIVE on PHOSPHORESCENT chalky paper instead of fluorescent chalky paper, and IMPERFORATE, possibly at the start of the printing some sheets were printed on this paper by accident in negative after placing the plate wrongly on the printing machine. After noticing the mistake the batch was destroyed and the paper roll was changed (to fluorescent paper). Great rarity, only one perforated example and 3 imperforate are known!