Step 1: You can dial *#06# on your phone to get your IMEI number. Also, you'll get it by going to Settings>About Device>Status.
Step 2: Once you get the IMEI, go to imei.info, input the number on the dialog box and hit Check
Step 3. The system will automatically shows the phone's information. If it shows something else than what your phone is saying, it is likelyto be a fake/cloned brand.