Lot
557 
Mexico, Airmail, 1929, 25c green & brown, imperf, trial color proof, full o.g., wide margins and bold colors, Very Fine and choice, a rare "issued" proof. Scott No. C3 var. Sanabria No. 15 Estimate $400 - 600.
On May 3, 1929, certain proofs or essays were sold at the post office in Mexico D.F. There were seven varieties in colors, perf and imperf, and a total of 225 examples all in toll were sold.
Realized: $425