As of 2015, a good place to have rare coins appraised is the Professional Coin Grading Service (PCGS). This company is highly recognized in the coin industry.
Customers can mail their coins into PCGS for appraisal. The company has appraised over 30 million coins valued at an estimated 29 billion dollars. The site is available in numerous languages and offers worldwide services.
Another location that can help determine the value of a rare coin is Coin Study. Coin price catalogs, and guidelines are also available on the site. The value of a coin is determined by its condition, its rarity and the demand for the coin.