"It has been common knowledge to informed collectors that many times the finest and rarest art glass is found unsigned"

This quote by James Lafferty suggests that knowledgeable art collectors realize that a few of the most important as well as rarest pieces of art glass are not signed. This indicates that the artist or maker of the item is unknown, making it tough to identify its beginning and value. It is feasible that the artist was not credited for their job, or that the piece was made before the method of signing art glass ended up being commonplace. It is also possible that the artist selected not to sign the item, either out of discreetness or to make it harder to recognize and worth. Whatever the reason, it is clear that the lack of a signature does not reduce the top quality or rarity of the item. Skilled art collection agencies recognize this and also are willing to pay a costs for unsigned art glass.