#C23C 1938 6c Ultramarine & Carmine Airpost Rare VF Used, Along with C23 Used for Color Comparison. International Buyers – Please Note. The item “#C23C 1938 6c Ultramarine & Carmine Airpost Rare VF Used Along with C23 Used” is in sale since Thursday, October 31, 2019. This item is in the category “Stamps\United States\1901-40\ Unused”. […]