How To Verify Original iPhone By Checking Serial Number and IMEI on Your iPhone
Every phone has a serial number and IMEI and so does every iPhone. They make difference between the original and refurbished iPhone because the serial number of every iPhone is assigned uniquely and can be checked on the official website of Apple, and the IMEI is also various from iPhone to iPhone. There are the serial number and IMEI on the box coming with the iPhone and thye should be the same as these in your iPhone.
To check your serial number and IMEI, please follow these steps：
Open Setting app on your iPhone. Tapping on “General”, click “About” and then scroll down. You will find the serial number and the IMEI soon.
Now you can check the serial number by visiting apple website if you get the message that sorry it is not valid, then it means your iPhone is not original.