Precious Metals Assaying Guide

Fire assay is the internationally accepted standard for determining the precious metal content of samples. The method involves combining the sample with lead and flux materials in a crucible, heating to high temperatures, and collecting the precious metals in a lead button.

The lead button is then cupelled — heated in a porous cupel to oxidise and absorb the lead, leaving a precious metal bead. The bead is weighed (parting assay) or assayed directly to determine the precious metal content.

Fire assay provides accuracy to within ±0.01% for gold and is the method specified by LBMA, LPPM and other international standards bodies for precious metal purity certification.

Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) is an alternative analytical method that provides multi-element analysis of precious metal samples. It is particularly useful for determining trace element composition and alloy analysis.

X-ray Fluorescence (XRF) analysis provides non-destructive surface composition analysis. While useful for rapid screening, XRF is less precise than fire assay for bulk composition determination and is typically used as a complementary technique.

AL AIN METALS uses fire assay as the primary methodology for precious metal purity certification, supplemented by ICP-OES for detailed composition analysis when required.

International precious metals trade requires assaying by accredited laboratories. LBMA-accredited assayers are preferred for gold and silver transactions, while LPPM accreditation covers platinum group metals.

Laboratory accreditation ensures the assayer operates to recognised quality standards, with calibrated equipment, qualified personnel and documented procedures. Accreditation is typically provided by national accreditation bodies.

AL AIN METALS uses independent third-party laboratories with appropriate accreditation for all precious metal assaying requirements.

An assay certificate documents the precious metal content of a sample, determined by an independent laboratory. The certificate typically includes the sample description, methodology used, purity result, laboratory identification and date of analysis.

For international trade, assay certificates should include the laboratory's accreditation details and be signed by an authorised representative. The certificate becomes part of the shipment documentation package.

AL AIN METALS provides assay certificates for all precious metal shipments, ensuring buyers receive verified purity documentation from independent accredited laboratories.