BS EN ISO 11426. Jewellery and precious metals. Determination of gold. Cupellation method (fire assay)
|Standard number:||20/30404745 DC|
|Status:||Draft for Comment|
- 39.060 Jewellery
This document specifies a cupellation method (fire assay) for the determination of gold on a material considered homogeneous. The gold content of the sample should preferably lie between 100 and 999,5 parts per thousand (‰). Finenesses 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.