Customs duty increase on gemstones and diamonds amends prior tariff entries and raises import duty under existing notification. Amendment substitutes the entries in column (4) of the Table in Notification No.50/2017-Customs for S.Nos. 349, 350 and 351, replacing each with a higher customs duty entry, effected by Notification No.68/2018-Customs issued under section 25 of the Customs Act and section 3(12) of the Customs Tariff Act, and stating the amendment's operative commencement as a further amendment to the principal notification.