ISO 11426 pdf download Jewellery — Determination of gold in gold jewellery alloys — Cupellation method (fire assay) Scope This International Standard specifies a cupellation method (fire assay) for the determination of gold ingold jewellery alloys. The gold content of the alloys should preferably lie between 333 and 999 parts perthousand (%o). The procedure is applicable specifically to gold alloys...