What is a Certificate of Authenticity, or COA?

The United States Mint issues Certificates of Authenticity with some  US coins intended for coin collectors. 

   Certificates of authenticity are sometimes called COA's.  Certificates of authenticity are usually printed on paper or thin card stock.  COA's often describe the coin or coin set and include a printed signature and statement from the Director of the Mint.  Additional wording will state that the coin or set is genuine and really issued by the government.  

Sample of a coin Certificate of Authenticity or C.O.A

Some coin dealers and serious collectors say COA's are  unnecessary.  They say, if a counterfeiter is going to make a fake coin, that can make a fake COA, too. You can almost hear them say, "For what's to keep a counterfeiter from printing a fake COA."  They might add, "if a counterfeiter can make a fake coin, they surely could print a fake Certificate of Authenticity."

Other collectors like the idea of having a COA with a coin because it gives them a feeling of realness and security with their coin ownership. 

Sample Certificate of Authenticity 

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Instead of having a COA, some collectors would rather have a coin that is graded and authenticated by one of the major coin grading services*.  The coin grading services often  encapsulate a coin after grading it. In the coin holder will be a label inside  that serves as a sort of certificate of authenticity and certificate of the coin's grade.

Certificates of Authenticity (COA) are a modern feature and seldom were they provided with coins from the mint prior to the mid-1980s.  So, don't expect a mint issued COA with most proof coin sets produced prior to those years.

*  PCGC, NGC, and ANACS are three of the most popular coin grading services.