How to check Mifare cards

There are a few things you can do to check Mifare cards.

- Use a smartphone torch and hold it up against the cards. This will confirm the antenna is inside that is rectangular in shape around the perimeter of the card edge. (see attached image)

- If you tap a card on an Andriod smartphone the phone normally will acknowledge the card (eg vibrates or pings) 

- Finally, if you can install the NXP NFC Tag info android app to verify the cards are ok.

 Mifare cards are highly reliable so  faulty packs of cards are not normally seen.