N.B.: All the major catalog publishers - Gibbbons, Michel, Minkus, Scott, etc. - deliberately alter the illustrations of overprints to deter forgers from using them as sources. This practice is clearly explained in either the front or endnotes of the catalogs, but this has not stopped "copycat" forgeries. ... An honest seller should permit you to buy "on extension for expertization" with full return privileges should the material not prove to be genuine. "Caveat Emptor!" (this is from SOSSI ; Scouts Stamp org. - aj.