A graded card's value sits in its label. Labels can be copied. Here is the verification order that catches most fakes, and the one attack it does not catch.
Before buying any graded card above pocket money, in this order.
Look it up directly on the grading company's own website and read the record. Do not follow a link from the listing.
Year, set, card number, subject, parallel. Any mismatch is decisive, so check this before anything else that costs time.
Typography, hologram behaviour under a tilted light, edge seams, glue residue, plastic cloudiness, flex. Look for anything that suggests the holder was opened.
All of the above verifies the holder. Resealed cases pass it. Material-level measurement of the card is what remains when the packaging checks out and the answer still matters.
Use a payment method with a dispute process, keep the listing, and inspect on arrival rather than after the return window.