While many valuable coins can require a keen eye and even a microscope to determine its value, the unique color of this state quarter makes its value obvious.

Here are 20 rare state quarters worth additional value, according to Gainesville Coins, USA CoinBook and PCGS.

United States quarters have been made with copper and nickel since 1965, though they may still look silver on the outside. Despite this, every now and then a special coin defies all standards. If ...

The 11-year program, "the 50 State Quarter program," ran from 1999 to 2008, during which each state was given a specific quarter design. Most U.S. state quarters retain their original value of $0.25.