The history of these beautiful gold and silver coins is what attracts some bullion buyers and coin collectors. These gold and silver coins were used as money in the U.S. in the 19th and early 20th centuries. They are now numismatic coins because of their age, their limited mintage, design uniqueness or a combination of factors. Coins of this era, including gold coins high graded and authenticated by industry-recognized agencies (PCGS, NGC, ANACS, IGC, CAC), such as the U.S. $20 Saint-Gaudens, the U.S. $20 Liberty and the $5 and $10 Indian gold coins, are the most popular semi-numismatic bullion coins sold.