Artwork validating artist
To evaluate a Certificate of Authenticity or COA, read Is Your Certificate of Authenticity Worth the Paper It's Printed On?
A statement, either verbal or written, from the artist.
Good provenance leaves no doubt that a work of art is genuine and by the artist whose signature it bears.
Unfortunately, numerous forged or otherwise misrepresented works of art are offered for sale with fake or questionable provenance at online auctions like e Bay, at fixed-price art websites and at bricks-and-mortar establishments, but nowhere is the proliferation of problem art and problem provenance more pervasive than at online auctions.
Documents that do not specifically describe the work of art in question do not constitute valid provenance.
* Photocopies of letters, certificates, and other documents are not valid forms of provenance (unless the originals are at a known location, and can be accessed and inspected firsthand).