A buyer's glossary: COA, hologram, LOA and grading terms

Certification terms

Certificate of Authenticity (COA) — a document from an authentication house stating that a specific signature was examined and judged genuine. It carries a serial number that resolves in the issuing house's own public lookup.

Hologram — a tamper-evident numbered sticker affixed to an item alongside or instead of a paper certificate. The number on the hologram is what you check against the issuer's lookup, the same way you'd check a COA's serial.

Letter of Authenticity (LOA) — a fuller written opinion, usually reserved for higher-value items, that describes the specific item and signature examined rather than just certifying a signature in the abstract. Where a listing carries a full letter rather than a sticker-only certification, the listing says so.

Witnessed autograph — the authenticator's own representative observed the signing happen, rather than forming an opinion on a signature after the fact from an item submitted later. Both are legitimate; a witnessed signing simply removes one layer of inference.

Grading terms (a different question from authentication)

Grade — a numeric score for physical condition, awarded by a grading service after examining centering, corners, edges and surface. A grade says nothing about whether a signature is genuine, and an authentication certificate says nothing about condition. See "Autograph authentication is not condition grading" on the authenticity page for the full distinction.

Slab — the sealed hard plastic case a graded card or item ships in after grading. The grade and certification number are printed on the slab's label.