CoinTrust app - gold/silver coins and bars sound verification for iOS and Android

How to Test Gold and Silver at Home: Proven Bullion Testing

Coin Tester on the App Store

Precious Coin Tester - Apps on Google Play

How to Test Gold and Silver at Home: Proven Bullion Testing

Pingcoin - Apps on Google Play

1 oz MintID Gold Bar .9999 Fine (NFC Scan Authentication)

Silver Gold Bullion Test App Review : Fooled? : Eye-On-Stuff

How to Test Gold & Silver at Home (5 Proven Methods) - Money

Gold Coin - Apps on Google Play

Silver Gold Bullion Test App Review : Fooled? : Eye-On-Stuff