Can anyone tell me how to check the originallity of 1 Rupee 1970 big coin. Someone told me that the original coin is non-magnetic but one of my friend is having this coin and its magnetic in nature. My friend is a professional coin collector and told me that only 1970 coin is magnetic and the coins 1971-1975 are non magnetic. I want to purchase this coin so plz tell me how to check its original.