Cut and polished gem-quality diamonds that have been worked beyond simple sawing but remain loose — neither strung, mounted, nor set — fall here, distinguishing them from both industrial-grade stones and finished jewelry. The Kimberley Process Certification Scheme governs the international movement of rough diamonds, but worked stones at this stage also carry compliance obligations around provenance documentation that importers must track carefully. Classification hinges on confirming the stone is non-industrial in character; diamonds intended for abrasive or drilling applications are excluded. Valuation complexity and high unit values make this heading a frequent focus of CBP audit activity.

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