Lot 10026 – 1889-91, Unissued 20c, die proof in black on chalk-surfaced paper with centre almost omitted

1889-91, Unissued 20c, die proof in black on chalky-surfaced paper, with the portrait in centre printed in light grey and representing the first state; as well as unissued 24c, die proof in black on card, showing the portrait in centre almost in albino and printed in light grey, representing the first state. Unlisted by Víctor Kneitschel in the « Tomo II » of his 1958 catalogue.