Question: what are the most rarest coins in the world?
Answer: 1804 Silver Dollar, Class I. This coin is often called the “King of U.S. Coins,” and for good reason—there are only fifteen known specimens of this silver coin in the world. ... 
1343 Edward III Florin. ... 
1787 Brasher Doubloon. ... 
1913 Liberty Head Nickel.