Authentication. Determining the genuineness of a numismatic item and its legality. The average person tests a coin for genuineness by weight, color, bounce and ring; a scientist by specific gravity and other tests. The numismatist, however, tests genuineness by comparison with existing specimens, noting minute areas of similarity and dissimilarity. The need for authentication increases when prices of genuine pieces rise attracting unscrupulous persons who fake these items. Technology for making a wide range of copies and replicas exists requiring the need for dedicated authentication.

For numismatic cataloging authentication exists for ascertaining the item at hand is not only genuine, but also the correct variety the numismatist claims it is. As the item could be genuine, but not the variety described. Thus the numismatist must bring a great deal of experience to the task of authentication, and must have numerous similar samples (same type and variety) to compare it with. Since this is so important for coins, particularly those of high cost, the need rose for a third party to ascertain the genuineness, this gave rise to the authentication service.