This is very genuine way I found to detect fake sd cards using
Fake Flash Test is another great tool to identify fake sd cards and flash memory devices.Here we have listed almost all procedure to find and provide information about how to find Fake memory cards from online retailer.
There is also an android app available on Google Play store that helps you to detect fake sd cards directly from your android device.This is very good micro sd card test software available on Google Play store for FREE.This Android app will write a test file and read it back testing it’s content to spot fake external memory of your device. It will test the speed and the storage capacity. Useful to check for a damaged or fake card.Check SD Card Tester Android App from Google Play Store.
Source : How to Verify Fake Micro SD Card