Brad Horn, a Hall of Fame spokesman, said the jersey, which had been purported to have been worn by Jackson when he and his teammates threw the World Series in 1919, "contained acrylic (coloring) that was first created in 1941," the New York Post reported Monday.
The item is the latest in a collection once belonging to Barry Halper, a collector who died in 2005, to be proven fake. A Ty Cobb diary from the collection, which was also donated to the hall of fame, has also been proven fake.
Peter Nash, a blogger and memorabilia collector who labeled the jersey a fraud in August, said about 10 percent of Halper's collection -- which his family claimed included about a million items -- was comprised of counterfeits.
2014: The Year in Music [PHOTOS]