Canada J31b

1974 Four cent red "Third Issue" on Hibrite Paper, upper right plate block of four showing the PRINTED ON GUM SIDE ERROR - the first multiple we recall seeing, in fact even singles of this error very seldom make an appearance on the marketplace, one of the rarest items of the 1967 Centennial Issue, Very Fine, Never Hinged (Unitrade J31b; catalogue value $8,000 for four singles)

Expertization: 2019 Greene Foundation certificate

QUITE POSSIBLY THE ONLY SURVIVING PLATE MULTIPLE. NO PRICE IS SHOWN IN THE UNITRADE SPECIALIZED CATALOGUE FOR A PLATE BLOCK – ANOTHER CLEAR INDICATION OF ITS GREAT RARITY.