Lot 50608 – Spanish Colonies, Río de Oro – 1907 4p, a unique copper

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.