How do I check if a PSA or CGC slab is real?

Look up the certification number printed on the slab's label in the grader's official database: PSA cert verification or CGC cert lookup. The result should match the card, set, number and grade on the label. If it doesn't match, or there's no record, don't buy. Also check the slab for signs of tampering. More tips: how to spot fakes.