GST on free sample to customer

Dear Expert
Please note:
1. We make tailor made product of customer for their ordering quantity.
2. One of the customer placed an order for a new product and as a sample of two pcs at rate of Rs.1.00.
2. The transaction price of the same categoryof goods is Rs. 150.00 per kg. And accordingly the value of such goods may be considered as Rs.9000.00 per pc considering the weoght of the goods.
3. This sample delivery may or may not bring a future order from the customer.
4. Even if this sample product is approved by the customer, they will not pay for the items supplied.

Now the point is whether gst is chargeable and if yes,then on which price?

The guideline may please be given with necessary section, notification circular, tweets etc.

Please also note that such sample is not a paper transaction to equalise the shortage / disposal etc.

Regards

Sujit Kumar Das
9433036600