Unsigned paintings can indeed be valuable. Because it is common for an artist's work of art to gain substantially in value after their death, a signature is not always necessary for the painting to have value. If the work can be authenticated, a painting will be valued primarily based on its artist.

Why would a painting be unsigned?

The reasons for this are varied: sometimes these works were not for sale while the artist was alive, and instead languished generally forgotten in their art studio or personal collection; or the buyer of a commissioned work requested that a signature not be added; or the artist simply forgot to sign it; or the artist ...

How can you tell if a painting is valuable?

One good indicator of how to tell if a paint is valuable is to figure out who owned the painting beforehand. If someone who was high up or well-known in the art community owned the painting, then there might have been a reason for it. They knew that it was worth more.