Colloidal Precious Metals

Colloidal dispersions of gold, silver, platinum, and other precious metals — where the metal exists as nanoscale particles suspended in a medium — serve advanced applications in diagnostics, catalysis, electronics, and specialty coatings. The entire heading resolves to a single 10-digit line (2843100000), and the high intrinsic value of the precious metal content means that accurate valuation and metal-content declarations are critical for customs compliance. Brazil leads US import supply, with the United Kingdom and Canada also among the primary sources. The nanoparticle form of these materials may also trigger review under emerging regulatory frameworks for nanomaterials.