PROCESSING
Gold and precious metals analysis: precision and transparency
Cormas offers an assaying service for materials containing gold, silver and platinoids. Determining the exact precious metal content is a critical step: not merely a technical procedure, but a guarantee of reliability and value offered to our partners.
Our methods: certified excellence
The correct assessment of the “fineness”, i.e. the purity of gold, requires sophisticated technologies and specialised expertise depending on the type of material and the intended outcome.
Cormas handles material analysis using various methodologies.
- Fire assay (cupellation): The principle of this method is based on the removal of all non-precious metals from a small weighed sample through oxidation during the cupellation stage. The sample is placed on a sheet of pure lead together with pure silver, in a ratio of 1 to 3 with the gold, so as to form an alloy containing 1/4 gold and 3/4 silver (hence the term inquartation). The lead melts together with the sample and the added silver, absorbing all the non-precious metals, which oxidise to form a liquid slag absorbed by the cupel, leaving a "bead" of pure gold-silver alloy. The silver is then separated in nitric acid and the gold is weighed to calculate the fineness. The reference standard is UNI EN ISO 11426:2021
- XRF Spectrometry (X-Ray Fluorescence Spectroscopy): this method uses X-rays to analyse the chemical composition of a material. When a material is irradiated with X-rays, the atoms it contains absorb energy and release this energy in the form of secondary radiation (fluorescence). By measuring the energy and intensity of this radiation, it is possible to determine the elements present in the material and their concentration. XRF is employed as a rapid screening and pre-selection tool, complementary to cupellation for official analyses
- ICP-OES Analysis (Inductively Coupled Plasma – Optical Emission Spectroscopy): this technique interfaces an inductively coupled plasma source with an optical detector (photomultiplier). The operating principle involves a flow of argon carrying the vaporised sample into an ICP torch, where it reaches temperatures of 6,000–8,000°C and undergoes ionisation and atomisation. The spectral composition of the emitted light is then analysed by a monochromator (diffraction grating) that splits the incoming light into spectra captured by the photomultiplier. ICP-OES is used for high-precision analysis of precious metals, even at trace levels down to parts per billion (ppb). The international standard for ICP-OES applied to gold is ISO 15093
What can be analysed
Our gold analysis service is aimed at industry operators who require assaying of their material or sample. It is possible to analyse jewellery manufacturing waste such as filings, crucibles and production offcuts, industrial and galvanic alloys, as well as investment gold and jewellery, second-hand gold and bullion.
Cormas: a trusted and expert partner for gold, silver and PGM analysis
Cormas offers full transparency because every stage of the analysis follows a codified procedure. The client receives a report certifying the result obtained. Cormas has a dedicated team of expert technicians capable of accurately interpreting analytical data, even on complex alloys, in a short turnaround time.