A Certificate of Authenticity is the single most misunderstood document in the art market. New collectors tend to treat it as a binary: the work either has one or it does not. Our curators treat it as a spectrum. A COA from the artist’s own studio or a recognized authentication body is load-bearing. A COA printed by a third-party retailer with no standing to issue one is decorative at best.
Knowing the difference is the difference between owning an asset and owning a framed guess.
What a COA is supposed to prove
A COA is a written attestation that a specific work is genuine, produced by or on behalf of the attributed artist, and consistent with the artist’s documented edition or catalogue raisonné. The critical word is “specific.” A credible COA identifies the work uniquely, not generically.
At minimum, our curators expect to see:
- Artist name, exactly as the artist signs
- Full title of the work
- Year of creation or publication
- Medium and substrate (e.g., screenprint on Coventry Rag 320 gsm)
- Dimensions
- Edition number in the form X/Y, or a designation such as AP, HC, PP with edition of X/Y for that category
- Name of the publisher or print studio
- Issuing body and a signature or embossed seal
- A unique certificate number or holographic marker
A document that is missing two or more of these fields should be treated as incomplete, not invalid, but incomplete.
Who can issue a credible COA
The issuer is more important than the certificate itself. The hierarchy our advisory practice uses, from strongest to weakest:
- The artist’s own studio or estate (Obey Giant Art, KAWSONE, the Warhol Foundation until 2012, the Keith Haring Foundation)
- Dedicated authentication bodies (Pest Control for Banksy, the Basquiat Authentication Committee until 2012)
- The original publisher or print atelier (Pace Prints, Gemini G.E.L., Counter Editions)
- The originating gallery, where a direct chain of custody is documented
- A reputable secondary-market specialist, with original documents referenced
- A third-party retailer with no relationship to the artist. This last category is not a COA; it is a sales receipt dressed as one.
Banksy is the cleanest example. No Banksy COA is credible unless issued by Pest Control. A gallery certificate, a seller’s affidavit, even an original gallery invoice are all secondary evidence, not authentication. Collectors who skip Pest Control are not buying a Banksy; they are buying a probability.
Red flags on the document itself
Our curators flag the following patterns during authentication review:
- Image on the COA does not match the work. A mismatch in edition number, cropping, or color is disqualifying.
- Signature on the COA differs from verified specimens. Artists’ signatures evolve but within bounds.
- Certificate number is missing, handwritten over a printed field, or duplicated across multiple works.
- Paper stock looks modern for a work purportedly from the 1980s or 1990s. Digital-printed COAs for pre-2000 works should be treated with caution.
- Holographic seals that are generic stock items sold on wholesale supply sites. Pest Control and KAWSONE, for example, use proprietary markers.
- COA references the work’s dimensions incorrectly. Dimensions should match the sheet, not the frame.
- Issuer’s address or website no longer exists, or was registered in the last 12 months.
The physical-work check
A COA is one half of authentication. The physical work is the other. Our curators always cross-check the following against the COA:
- Edition number in pencil, bottom-left or lower margin, in the artist’s hand
- Signature in pencil, bottom-right or lower margin
- Embossed chop or blindstamp from the publisher, usually in a lower corner
- Paper weight, deckle edge, and substrate consistent with the edition’s documented specification
- Registration marks, plate tone, and ink coverage consistent with other known copies of the edition
A COA that perfectly describes a work whose physical attributes do not match the edition’s known specification is a forgery signal, not a pass.
Blockchain-backed COAs
A growing share of contemporary editions now include a blockchain-backed certificate, typically an NFT tied to a physical work with a QR code on the printed COA. Our curators treat this as a useful supplement, not a replacement. A blockchain record proves that a specific token was minted at a specific time by a specific wallet. It does not prove that the wallet belonged to the artist, or that the physical work matches the token. The chain is only as good as the issuer’s identity controls.
For a deeper treatment of how this is evolving, see our piece on blockchain authentication linked below.
When in doubt, do not buy
The single most valuable habit a collector can build is comfort walking away. A COA that raises three or more flags in the checks above is not worth negotiating on. The market moves constantly. Another copy of the same edition will surface. The cost of passing is zero. The cost of buying a forgery is the purchase price plus the reputational cost of trying to resell it.
