How to export gift items from india

Yes, you can send the gift but you need to declare the same in the Customs invoice and shipping Bill mentioning that " Free Gift No commercial value,value declared for Customs purpose only.".You may show the value of Gift USD 100/-  for Customs clearance purpose.

Further, you should also show the same contant   " Free Gift No commercial value,value declared for Customs purpose only." with USD 100/- in the Commercial invoice also so that the consignee can clear the same along with other item as suppplied by you.

Shipping line may mention in the BL because the BL is prepared on the basis of shipping Bill.

one more query, we have imported machinery part and paid import duty but the supplier has supplied wrong part so we want to return it. now my queries are

if we replace the wrong part with new one then what is the procedure and can we get import duty paid on it? 

if we dont replace it but only return it then what will be the procedure and can we get import duty paid on it?

You can export the defective part and after completion of export, duty drawback shall be claimed on the duty paid at the time of import.  This shipping bill needs to be filed under Sec 74 with a drawback claim.  The maximum refund you would get would be 90% of duty paid.

The import of replacement material needs to be treated as a fresh import and applicable duty to be paid.

But the defective part should be identifiable by the Customs authorities of port of export  that the same was imported.