Proof $20 Liberty Head gold coins, known as double eagles, have always been a favorite of affluent collectors and investors of original U.S. gold coins. At the Central States Numismatic Show, an 1883 double eagle certified by PCGS in Proof 64 Deep Cameo sold at auction for $204,000. A significant sale considering the last 1883 double eagle in PCGS Proof 64 Deep Cameo sold for $158,625 in August 2014. Much like the famous 1895 Morgan dollar, which is known only through proof strikes, no 1883...