1. Check the certification number: each PSA-certified article has a unique certification number, which can be found in PSA official website. If the number can't be found or the query result doesn't match the item, it may be forged.

2. Check the certification label: PSA-certified projects will have a label with PSA logo, which will contain information such as certification number, project description and signer. If the label is unclear or inconsistent with the information in official website, it may be forged.

3. Compare signatures: If it is a signed item, you can compare it with other works of the signer to see if they are consistent. If the signature is inconsistent or inconsistent with other works of the signer, it may be forged.

4. Seek professional help: If you have doubts about the authenticity of the goods, you can seek professional help, such as auction houses and appraisal institutions.