Mexico, 1861, 2r black on pink, half used as 1r, Guanajuato, left half without district overprint, in combination with 1861, 4r black on yellow, half used as 2r with overprint on 1861 folded letter to Mexico City, tied by blue Guanajuato oval handstamp (Schatzkes 472), Very Fine, an extremely rare and quite possibly unique bisect combination usage; with 1981 and 2008 MEPSI certificates, signed Calves. Scott No. 8b  Estimate $4,000 - 6,000. $0 (Image)