Possible Clues:

• Dictates one way to prove gold genuine
• Cat's diet (anag.)
• Rigorous process, biting banker
• Dictates metamorphosis in the final analysis
• Conclusive procedure
• A police exam that's hard to pass
• 'Appraisal to show the true value (4,4)'
• Litmus paper is used for it
• Credibility determiner
• Conclusive proof provider