This post explains the difference between the authenticity vs. attribution of an artwork. I found this list most helpful.
For example, if you are looking for a work by Pablo Picasso consider these terms:
- Pablo Picasso: The auction house believes this is an original work by the artist
- Pablo Picasso (replica): The auction house believes that the artist him/herself made this work as a replica of their own, previous original.
- Pablo Picasso (attributed to): The auction house finds it likely that this is an original work, but is not prepared to guarantee this.
- Pablo Picasso (his studio): The auction house believes that the work was made in the artist’s studio and possibly under his supervision.
- Pablo Picasso (his circle): The auction house believes that the work was made by another artist but during the lifetime of the named artist and in their manner.
- Pablo Picasso (follower of): The auction house believes that the work was done in the manner of the named artist, during their lifetime or later.
- Pablo Picasso (in the manner of): The auction house believes that the work is done in the manner of the named artist but after their lifetime.
- Pablo Picasso (after): The auction house believes that the work was made by another artist, based on an original work by the named artist.