How can I tell if a signed artwork is authentic?

A signature alone does not prove authenticity, since signatures can be added or forged. Look at the whole picture: the style, materials, technique, and condition should all be consistent with the artist and the period. Labels, stamps, gallery stickers, and inscriptions on the back can provide helpful clues.

Provenance, or the documented ownership history, is one of the strongest supports for authenticity. Receipts, exhibition records, letters, and photos showing the work in a past owner's home all help. For some well-known artists, recognized experts or catalogue raisonne committees may be the accepted authorities.

For valuable work, consult a qualified appraiser or a specialist with expertise in that artist. Be cautious about certificates from unknown sources, since they are easy to fake. When buying, ask the seller what documentation exists and whether they will guarantee authenticity in writing.