National Grid Company

Numismatic Guaranty Company (NGC) is an international third-party coin grading and certification service based in Sarasota, Florida. It has certified more than 60 million coins. NGC certification consists of authentication, grading, attribution, and encapsulation in clear plastic holders. NGC is a subsidiary of Certified Collectibles Group (CCG), which owns six collectible certification services and is in turn owned by Blackstone, a multibillion-dollar New York City hedge fund.