1858 Argentina SG 8 & SG9 Assumed to be Gibbons forgeries. Details below...

In 1871 Stanley Gibbons purchased the Lithographic stone of the 5c value of the 1862 issue of Argentina from the printer Robert Lange. From it, he not only produced large quantities of unofficial reprints from this 5c value, but he also had the value altered to 10 & 15c and thus produced the complete set of 3. These two are believed to be two of his forgeries