Last updated Oct 12, 2026. Educational only; we don't authenticate items.
Witnessed brand or league programs. The company or league witnesses the signing and applies a numbered hologram, as described by Upper Deck [1], TRISTAR [2] and MLB [3].
Third-party authenticators. An outside company examines an existing signature and gives an opinion. PSA/DNA [4] and Beckett [5] describe comparing signatures against exemplars and then applying a tamper-evident label.
Seller-issued COAs. The seller writes its own certificate. The FBI's Operation Bullpen found that forgers often supplied COAs, including blank forms filled in by distributors [6].
eBay says a COA is only as valuable as the reputation of whoever issued it, and it lists some issuers whose COAs it does not allow [7]. Whatever the source, run the issuer's lookup and compare the record with the item (see How to verify a COA).