Start with the cert, but don't stop there
Enter the number at PSA's cert verification page and compare the card, grade and any images on record with the slab. If the record shows a different card, walk away.
PSA itself warns that a matching number doesn't prove authenticity: counterfeiters copy real cert numbers and labels.
Inspect the weld and edges
PSA describes its holder as tamper-evident, not tamper-proof, because the two halves are sealed with a sonic weld. A holder that was opened and reglued can show frosting, tiny cracks or a seam that separates or flexes.
Compare the holder's shape and edge profile with a known genuine PSA slab from the same period. PSA has changed holder construction over the years.
Inspect the label
Check fonts, spacing, the hologram and the label's alignment against genuine examples. A real label moved into a fake holder is a known scam, so a perfect label doesn't clear a suspicious case.
Check the card itself against the grade. A card with obvious wear in a PSA 10 holder is a red flag even if everything else matches.
Reduce the risk when buying
Buy expensive slabs from sellers with a track record and a return policy, or through a platform that holds the card in a vault. Pay with a method that offers buyer protection.
If something looks off, ask for more photos or video before paying, and compare the price with recent sold comps.