Scott C6 1923 24c Biplane Airmail Issue Mint Graded XF 90J NH with PSE CERT Updated on September 17, 2023 By admin Comments Off Certificate states: it is genuine unused, o. American Philatelic Society Member #178998. Share Tweet By admin You May Also Like U. S. (Scott C13) AIRMAIL 65¢ GREEN GRAF ZEPPELIN (MFNH) FINE, NEVER HINGED US Scott #C3 Airmail Single VF Mint Never Hinged Issued 1918 Fast Plane Variety