… and so is the case with this item, an agent’s certificate from the National Ink Co. issued December 21, 1865. The philatelic usage is mundane, although it’s nice to have a clear “N. Ink Co.” manuscript cancel.

No in this case, it’s the certificate itself that has all the appeal. A patriotic eagle vignette, and more importantly 3-color printing in red, blue, and metallic gold. That level of expense was by far the exception rather than the rule in that era.

Gorgeous piece IMO.