Certified Guaranty Company, also known as CGC, is a Sarasota, Florida comic book grading service.

People sending in comics themselves can get a 10% discount from CGC by using the "Internet Partners" links on their submission page.

A label is affixed at the top indicating the title, date, grade, page quality, and any notes, such as notable creators.

[6] Prior to advent of CGC grading and authentication services, collectors, buyers, and sellers were at the mercy of the marketplace.

There was a clear possibility of a conflict of interest as a seller would benefit from exaggeration of the condition to inflate the value and thus increase profits.

[11] This underscores CGC's ability to provide a grading service as a neutral third party from a transaction, this created a degree of impartiality that did not exist before.

Furthermore, the CGC establishes a chain of custody of that specific comic until it is “slabbed” and subsequently returned to the individual who ordered the signature series grading and verification.

Similarly, a comic book marked by CGC with the purple "Restored" label can suffer a significant price reduction.