Best known as the home of The Overstreet Comic Book Price Guide, Gemstone Publishing was formed by Diamond Comic Distributors President and Chief Executive Officer Stephen A. Geppi as a conduit for his efforts in preserving and promoting the history of the comics medium. Most recently, Gemstone and Disney Publishing Worldwide announced plans to publish Disney Comic Books featuring many of the beloved characters that had not appeared on comics shop shelves for years, including Mickey Mouse, Minnie Mouse, Donald Duck, Goofy, and others.

Furthermore, Gemstone separately acquired Russ Cochran Publisher and Overstreet Publications, which brought with them The Complete EC Library and the noted line of price guides, respectively. As a result, Gemstone also publishes The Overstreet Comic Book Grading Guide, The Big Big Overstreet Comic Book Price Guide, Hake's Price Guide to Character Toys, The Overstreet Toy Ring Price Guide, and The Overstreet Indian Arrowheads Identification and Price Guide, and co-published Tales of Terror! - The EC Companion with Fantagraphics Books.

In addition to these projects, Gemstone publishes Comic Book Marketplace, a monthly magazine for comic book collectors. In 2002, Gemstone added Scoop, a free, weekly information e-mail newsletter, to its list of popular publications.