the battery seems to be original , did you get the battery with-in the box ? if so , yes it 100%orignal if the box was sealed packed (I believe you are from India )
Lumia 520 has BL-5J battery , 1430mAh , 3.1V 5.3Wh
its a rechargeable li-ion battery , yes it's original :smile: but I am worried about the dent / mark on the battery ?