Fire Assay (Cupellation Method)
Fire Assay is a testing method used to determine the gold (Au) content in alloy samples that contain copper (Cu), silver (Ag), and zinc (Zn). This technique is based on the cupellation process, which provides highly accurate and reliable results.Standard Reference
This method is conducted in accordance with the international standard:
ISO 11426:2021 – Jewellery — Determination of gold in gold jewellery alloys — Cupellation method (Fire Assay)Applicability and Limitations
The Fire Assay method is not suitable for samples containing other metals such as:
- Platinum (Pt)
- Rhodium (Rh)
- Ruthenium (Ru)
- Nickel (Ni)
- Or other elements classified under the Platinum Group Metals (PGMs), which include six rare, precious, and highly valuable metals: platinum, palladium, rhodium, ruthenium, iridium, and osmium.
These metals may remain mixed with the gold during cupellation and cannot be completely separated, which may result in inaccurate or overestimated gold content. The limitations of this method are clearly specified in the relevant ISO standard.
Laboratory Accreditation
Bangkok Assay Office Co., Ltd. is accredited under the standard:
TISI ISO/IEC 17025:2017 (equivalent to ISO/IEC 17025:2017)
by the Thai Industrial Standards Institute (TISI)
- Accreditation Number: TESTING 1816
- Scope of Accreditation: No. 25-LB0066
- Gold (Au) testing range: from 33.62% to 99.52%
All testing is performed by certified personnel using validated procedures to ensure the highest level of accuracy and compliance with international standards.
