Quick search by citation:

19 U.S. Code § 3903 - Measures for the importation and exportation of rough diamonds

(a) Prohibition

The President shall prohibit the importation into, or exportation from, the United States of any rough diamond, from whatever source, that has not been controlled through the Kimberley Process Certification Scheme.

(b) WaiverThe President may waive the requirements set forth in subsection (a) with respect to a particular country for periods of not more than 1 year each, if, with respect to each such waiver—
(1)
the President determines and reports to the appropriate congressional committees that such country is taking effective steps to implement the Kimberley Process Certification Scheme; or
(2)
the President determines that the waiver is in the national interests of the United States, and reports such determination to the appropriate congressional committees, together with the reasons therefor.
Statutory Notes and Related Subsidiaries
Effective Date

For effective date of this section, see section 15 of Pub. L. 108–19, set out as a note under section 3901 of this title.

Executive Documents
Delegation of Functions

For assignment of functions of President under subsec. (b) of this section, see section 2 of Ex. Ord. No. 13312, July 29, 2003, 68 F.R. 45151, set out as a note under section 3901 of this title.