The map seemed to be an unbelievable find, an unknown fifth original of the rarest of documents, a vision of the world, circa 1507, by the famed German cartographer Martin Waldseemüller. It features 12 so-called globe gores — like a world map drawn on an orange peel that has been sectioned and squashed flat.

Designed to be cut out and pasted around a sphere, these creations of Waldseemüller are thought to be the first printed globes ever made, as well as the first maps ever to use the name “America.”

Christie’s, the auction house, estimated the new find would fetch from $800,000 to $1.2 million when it went on the block Dec. 13 at its London salesroom.

But something about the map didn’t seem right to Alex Clausen, a San Diego-based rare-map dealer, who compared it to high-resolution images of the other known copies.