Detail as per standard catalog :
Note : These coins were made of Aluminium Magnesium Alloy wrongly mentioned as Aluminium in standard catalogs.Refer Kolkatta mint link for more details : Click Here
Diamond below the year on reverse face of coin represent Mumbai Mint coin , star represent Hyderabad mint coin and no mark represent Kolkata mint coin.
Reverse Part of Coins :
Observe face of the coin :
Click on any image above to have a look at zoomed high clarity image.