Cert number: how to check a graded card's certification

A cert number, short for certification number, is the unique number a grading company prints on a slab's label and records in its own database, so anyone can look it up on the grader's website and see which card and grade it was issued for. PSA, CGC, Beckett and TAG each offer an online lookup.

It's often more than a number check. CGC images every card it grades, and PSA shows scans for many of its slabs, so a lookup can show you photos of the card taken at grading.

Before you buy one

• Check three things. The number exists, the card and grade in the lookup match the listing, and the number in the photo matches any number in the description. eBay asks sellers of graded cards to add the certification number, so look in the item details first.

• Don't stop at a match. A match proves the number is real, not that the slab in the photo is the original. PSA warns that counterfeit labels are made with real cert numbers taken from public sources. Where the lookup has grading photos, compare them with the card in the listing.

• Know what eBay's check covers. For eligible cards, eBay's Authenticity Guarantee has PSA inspect a graded card's holder for tampering and check that the case and label are authentic before it ships; it doesn't regrade. It covers US buyers and slabs from PSA, SGC, CGC (and CSG) and BGS. On an eligible slab, look for it on the listing.

• If a lookup won't load, ask for photos. Ask the seller for sharp shots of the front and back of the slab, label included.

A ChaseBoard watch can be set to Authenticity Guarantee only, and when a PSA slab listing gives its cert number, the alert links straight to that number on PSA's site, so the first check is one tap away.