A forgery of the 1862 10c green ‘small shields’ stamp originally issued by Argentina.
Many forged versions of this stamp exist, as noted in this interesting blog post, apparently produced by the original printer, Roberto Lange, a few years after the real issue. The narrow and closed ‘C’ in centavos distinguishes this reproduction from the (much more valuable) real thing. Still, it is collectable as a curiosity in its own right.
U/M / Unmounted Mint / MNH / Mint Never Hinged.