IGST on Imports and Exports

On Import   of Goods you  have pay IGST  on RCM    and  Export  is   Zero  rated ( No  GST )   supply  under  GST  law ,  you can  either  export  the goods  by paying  IGST and  then claim  refund  or  through   LUT /BOND   subject  to conditions . 

Dear Rohit

If you have imported goods means the goods had been crossed the custom barrier of Indian & brought into India , then you exported the same to some other country , then follow the reply by Mr. Prasad.
And if the goods are never entered into India , & sent from one country (Non taxable territory) to another , then it cover under schedule III , hence there is no GST . It's neither a supply of goods nor supply services