How to check if you Samsung is original, Fake or Refurbished?

There are few methods which are written below

1.Check Serial Number:
First off all remove back cover and battery then look for serial number under the battery

Keep serial number in mind or write it.
Then turn of the cellphone and follow these steps
1.Go to setting
2.About Device
3.Status
4.Scroll and look for serial number

If both serial numbers are different then its fake. If serial number is same then its original.