We offer The Best of the Stamp collecting true gems of Postal history
Inverted Center Stamp Persiphila 532-40PBCI, Scott 562; MNH.
1914 Coronation "Qajar Crown" 3c, perf 11 x 11.5 all PRINTED BOTH SIDES, one side with INVERTED CENTERAccording to Sellinger, over 200 exist.
Some stamps used to require a second or third manual feed through the printing press after changing the ink in the press. When the sheet was accidentally fed upside-down for its second passage through the press, an inverted centre would result.