Spanish Colonies, Río de Oro - 1907 4p, a unique copper plate of the 4p error of colour in se-tenant pair with 3p; an exceptional discovery from the Sperati archive and evidence that Sperati printed the Río de Oro 4p error of colour both from a copper plate and with his standard technique of photolithography; the B.P.A. just recorded one single proof of impression of a 4 p+3 p se tenant pair. (Image)

Spanish Colonies, Río de Oro - 1907 4p, a master negative cliché on film of the 4p error of colour in se-tenant pair with 3p, showing hand painted surround to concentrate the light on the area of design, and, incidentally, the serial numbers on the back of the stamps which have been also transposed; a unique documentation which, together with the copper plate above, evidences the dual reproduction process by which Sperati created the Río de Oro error of colour. (Image)

Spanish Colonies, Río de Oro - 1907 4p, error of colour in se-tenant pair with 3p, glass support cliché in bright vermilion bordering on orange with reversed image, showing manuscript dating “6/29” and some faint production notations at base. (Image)

Spanish Colonies, Río de Oro - 1907 4p, error of colour in se-tenant pair with 3p, die proof on pelure paper in black and with dark border painted around the design, with succinct technical comments at base, including “press. 6.5” likely related to the set-up of his press and thus evidence of his printing from an engraved die; a unique and highly significant documentation. (Image)

Spanish Colonies, Río de Oro - 1907 4p, error of colour in se-tenant pair with 3p, die proof on wove paper in black and with dating “8/26”. (Image)