Lot 10017 – 1889-91, “Rivadavia” & “Sarmiento” 5c and 6c in two proofs during the first process of engraving

1889-91, “Rivadavia” & “Sarmiento” 5c and 6c in two proofs printed in blue on thin paper, the former cut a bit into at right with a blurred impression, the latter showing a proof of the frame with four crossed lines originating from the angles and the halves of each side with the purpose of determining the centre in the design where to apply the image of the portrait before platemaking, both produced during the first process of engraving. A unique duo.