Export controls on rough diamonds require Kimberley Process certification; classification and alloy rules govern pearls, stones, and metals exports. Chapter 71 classifies articles wholly or partly of pearls, precious or semi precious stones, precious metals or metal clad with precious metal into specified headings, defines 'precious metal' and 'metal clad with precious metal', and treats alloys as alloys of a precious metal where any one precious metal constitutes two percent or more by weight. The Schedule lists exclusions, sub heading rules and product-level HS codes; most items are designated Free for export. Export of rough diamonds requires a Kimberley Process certificate, and certain SCOMET Category 0 items require Department of Atomic Energy authorization.