Jewellery and precious metals — Determination of gold — Cupellation method (fire assay)

Adopted by the Council as a standard on 13/04/2026

Sector: Mechanical and Metals

Project Method: Adoption without modification

Project Type: New

International Classification for Standards (ICS)

Code	Classification
39.060	Jewellery

Adopted Standard

	Standards / Amendment / Corrigendum
1	ISO 11426-2021

Scope

This document specifies a cupellation method (fire assay) for the determination of gold on a material considered homogeneous. The gold content of the sample lies preferably between 100 and 999,5 parts per thousand (‰) by weight. Fineness above 999,5 ‰ can be determined using a spectroscopy method by difference (e.g. ISO 15093).
The procedure is applicable to most types of gold samples. Some modifications are indicated for specific cases (presence of large amount of base metals, platinum or palladium, silver). It is not compatible with the presence above trace levels of iridium, rhodium and ruthenium (more than 0,25 ‰ for the sum of all three elements).
This method is also intended to be used as the recommended method for the determination of fineness in jewellery alloys covered by ISO 9202.