Retrospective exemption from customs duty on imported rough diamonds removes past duty liability for affected importations. The Central Government directed a retrospective exemption from customs duty on imports of 'Rough diamonds (industrial or non-industrial)' for the period 1 July 2017 to 1 February 2022, noting a generally prevalent practice of non levy of duty; it further explained that an amendment later required Kimberly Process Certification for simply sawn diamonds, and therefore any duty otherwise leviable under the First Schedule read with the notification shall not be required to be paid for imports in that period.