I try getting information on internet on how to find out whether my Samsung is original or not and find website that stated that we can check through IMEI number .
So I already try and based on the website if the information appear after we put the IMEI number is the same with our phone model thus it is original
I dont know how far the truth of the website . But U guys can try .

Here are the link of the website : http://www.imei.info/