This one is a Spiro Brothers forgery of the "crown and posthorn" series 3c stamp of 1874. The genuine stamps are on watermarked paper, and the lettering is sharp and clear. Most notably, the Spiro forgeries lack a hyphen between "DANSK" and "VESTINDIE".
From Varro Tyler's Focus on Forgeries
, "Within two years of their appearance, the five original values of this definitive series first issued in 1874 were imitated by the Spiro Brothers in Hamburg, Germany. The original stamps were printed by typography (letterpress). The forgeries, which are still common, were reproduced by lithography."