A few years ago, I bought an auction catalog from Book Sale describing Sale 1040 of the Robert A. Siegel Auction Galleries (“Outstanding United States Stamps,” March 26-28, 2013). My favorite stamp in the catalog is the one shown here (lot 1211). (I got the image from http://www.usphila.com/us/stamp/price/scott-17-page-8.) Estimated to sell for US$ 6,250, it sold for US$ 5,750.
Although some people consider the stamps in the Columbian Issue or in the Trans-Mississippi Issue to be the most beautiful United States postage stamps, for me this United States 12c Black (Scott 17, issued in 1851) is the most beautiful U.S. stamp I have seen.
Joel Reyes Noche 