What Is a COA?
A certificate of authenticity is a statement that an autograph is genuine. Who made that statement is what matters.
Published · 5 min read · By CollectorFish
The basics
A COA, or certificate of authenticity, is a document stating that an item is genuine. In autographs, COAs come from several kinds of issuers: the seller or dealer, the organizer of a private signing, the person who signed, or an independent third-party authentication company.
The paper itself proves nothing. Anyone can print a certificate, and counterfeit certificates exist. What gives a COA meaning is the reputation and independence of whoever issued it, and whether you can verify it.
Kinds of COAs
- Seller or dealer COA: the seller’s own statement. It can be useful when the seller has a long, checkable track record, but it isn’t independent.
- Signing or event COA: issued by the promoter of a signing the item came from. It documents provenance, especially when it carries a number tied to the event.
- Third-party COA or letter: an opinion from an independent authentication company, usually with a certificate number, and often a matching sticker or hologram on the item.
A full letter of opinion (sometimes called an LOA) typically describes the item in more detail than a short certificate card. The School of Knowledge covers COA vs. LOA in more depth.
How to check a COA
- Look up the certificate number on the issuing company’s own website, typed in yourself rather than from a link provided by the seller.
- Compare the record’s description and any photos with the item: same person, same item type, same inscription.
- Check that any sticker or hologram number matches the certificate.
- Be wary of certificates with no issuer contact details, no number or vague wording such as “guaranteed authentic” without saying by whom.
A COA is not a guarantee
Even a respected third-party COA is an expert opinion. Opinions can differ between authenticators, and buyers should still do their own due diligence. See autograph authentication explained.
COAs on CollectorFish
CollectorFish sellers choose how an autograph was authenticated or obtained and can add a certificate number, which is shown on the listing as “Authentication stated by seller”. CollectorFish doesn’t verify certificates or authenticate items. Counterfeit certificates and knowingly false authentication claims are prohibited by the Marketplace Rules.
This guide is general collector education, not a guarantee of authenticity or value. CollectorFish does not currently authenticate or appraise items.
Related guides
Authentication is an expert opinion about whether a signature is genuine. Here is how it works and what it can and can’t promise.
Collectors often ask which authenticator is “best”. This guide doesn’t pick one. It explains how these services work and what to check for any of them.
Most problems can be avoided before you pay. Here is what to check, what to ask and how to pay.
A personally obtained autograph was signed in front of the person selling or describing it. The claim is only as strong as the evidence behind it.
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