Known to coin collectors as “slabs,” these are the product of third party coin grading services. “Third party” because these services do not buy or sell coins, but instead provide expert authentication and grading of coins by a panel of experienced numismatists.

The leading services are PCGS (Professional Coin Grading Service) and NGC (Numismatic Guaranty Corporation.) Coins are submitted to these companies by collectors for a fee that varies with the anticipated value of the coin.

Grading services came about during the 1980s as a consequence of surging rare coin values at auctions, coin shows, and coin shops worldwide. From the end of WW II, coin collecting in the US had grown each year. Grading standards were rather loose by today’s standards, though organizations such as the American Numismatic Association did publish their own authoritative verbal descriptions of each grade for each US coin type.

Still, it was up to each seller to interpret these standards. As coin prices advanced, an incorrectly graded coin could be mispriced by a substantial dollar figure.

While third party coin grading does not remove all subjectivity from the process, it does substantially reduce the risk of an incorrect grade by relying on graders without “skin in the game.”

Visit us at London Coin Mission Viejo to see our current inventory of graded coins and discuss this fascinating subject further.