During the Renaissance, many painters took on apprentices who studied painting techniques by copying the works and style of the master. As a payment for the training, the master would then sell these works. This practice was generally considered a tribute, not forgery, although some of these copies have later erroneously been attributed to the master.
The principles of archival provenance were developed in the 19th century by both French and Prussian archivists, and gained widespread acceptance on the basis of their formulation in the Manual for the Arrangement and Description of Archives by Dutch state archivists Samuel Muller, J. A. Feith, and R. Fruin, published in the Netherlands in 1898 (often referred to as the "Dutch Manual").
Further complicating matters, following Man Ray's death, control of printing copyrights fell to his widow, Juliet Man Ray, and her brother, who approved production of a large number of prints that Man Ray himself had earlier rejected. While these reprints are of limited value, the originals, printed during Man Ray's lifetime, have skyrocketed in value, leading many forgers to alter the reprints, so that they appear to be original.
A qualified authority is a difficult concept, because it’s more than claiming (or seeming) to be an expert. This individual needs to have significant background and experience with the artist. Such as published papers about the artist, or perhaps they teach courses, or have catalogued essays about this artist. Of course the artist themselves, relatives, employees and descendents of the artist are understood as a qualified authority. Once you have all of your documents corroborated and stored in your Artwork Archive account, you can have peace of mind.
Excluded from the category of literary forgeries is the copy made in good faith for purposes of study. In the matter of autographs, manuscripts in the handwriting of their authors, forgeries must be distinguished from facsimiles, copies made by lithography or other reproductive processes. Some early editions of Lord Byron’s work, for example, contained a facsimile of an autograph letter of the poet. If such facsimiles are detached from the volumes that they were intended to illustrate, they may deceive the unwary.
In the 18th and 19th centuries, the mania for classification and study of the past resulted in an upsurge in forgeries as the art market adjusted to accommodate the new interest in the artistic past. That interest in the classification of the past also led to the founding of academic disciplines such as the history of art. The study of art history and the creation of agreed-upon bodies of work for artists and eras, as well as advances in science, made possible in the 20th century the winnowing out of forgeries, fakes, and misattributions from authentic works. As art historians gained more knowledge about the past and the styles, materials, and working conditions of artists and historical epochs, inauthentic and fraudulent works were more readily exposed.