Rapid, certified fire assay and XRF testing to determine the exact gold content of your material — with accuracy to one part per ten-thousand.
An assay is a precise analytical test that determines the exact gold (and silver) content of a metal sample. Before any gold can be traded, refined, or exported, an accurate assay is essential — it establishes the true value of your material and forms the legal basis for any transaction.
At Oasis Gold Refinery our accredited laboratory employs two world-standard techniques: Fire Assay — the most accurate method in existence, legally recognised for gold hallmarking, accurate to one part per ten-thousand — and XRF (X-Ray Fluorescence) Spectrometry, a rapid, non-destructive screening method that delivers results in minutes.
Both methods are used by the world's largest refineries and mining companies. Our certified assay reports are accepted by Uganda's Directorate of Geological Survey and Mines (DGSM), Uganda Revenue Authority (URA), and international gold buyers and banks.
We apply the same analytical techniques used by LBMA-accredited refineries and international mining laboratories — delivering results you can trust.
Fire assay is the most accurate precious metals testing method in existence and the legal standard for gold hallmarking worldwide. It has been used for over 4,000 years and remains the definitive technique for precious metal analysis.
How it works: A precisely weighed sample (the "charge") is mixed with a flux of litharge (PbO), silica, borax, and soda ash, then heated in a furnace above 1,000°C. The lead from the flux collects all precious metals into a "lead button" as the rock matrix dissolves into slag. The lead button is then placed in a porous ceramic cupel and heated again — the lead oxidises and is absorbed into the cupel, leaving behind a tiny doré bead (prill) containing only gold and silver. This bead is weighed, then parted with nitric acid to separate the gold from silver. The pure gold prill is weighed again — giving an absolute measurement accurate to 1 part per 10,000.
Fire assay is a destructive test — a small portion of your material is consumed. However, the gold recovered from the assay portion is credited back to you in your settlement.
X-Ray Fluorescence (XRF) spectrometry is a non-destructive analytical technique that identifies and quantifies the concentrations of elements in a sample by measuring the characteristic fluorescent X-rays emitted when the material is irradiated with a primary X-ray beam.
How it works: When X-rays strike the sample, they displace electrons from the inner shells of atoms. As higher-energy electrons fill these vacancies, they emit fluorescent X-rays at wavelengths unique to each element. By measuring the intensity and wavelength of these emissions, the XRF instrument determines the elemental composition of the sample in seconds — with no sample destruction.
XRF is ideal for rapid field screening, incoming goods verification, and parcel valuation. Studies show XRF accuracy is typically within 0.1–0.2% of fire assay results for large, flat, homogeneous samples. For irregularly shaped parcels, the margin is within 0.5%. We use XRF as a fast first-pass screen; fire assay is always used for final settlement and certification.
A 4,000-year-old technique refined to perfection — each step performed under strict ISO-aligned laboratory controls at Oasis.
Material is homogenised, pulverised, and a precise charge weight is drawn — witnessed and logged.
Sample is mixed with litharge, silica, borax, and soda ash in exact proportions determined by material type.
Crucibles are fired in the muffle furnace at 1,000–1,100°C. The lead button collects all precious metals from the molten slag.
The lead button is placed in a porous cupel and oxidised — lead is absorbed, leaving a pure doré bead of gold + silver.
The doré bead is treated with nitric acid to dissolve the silver, leaving a pure gold prill which is weighed precisely.
Results are calculated, verified, and issued as a signed fire assay certificate — legally binding and DGSM-accepted.
Every assay performed at Oasis Gold Refinery results in a formally issued, signed, and stamped Assay Certificate. This document is the legal basis for all gold trading, refining, and export transactions and is accepted by:
Rush same-day certificates are available for urgent commercial or export requirements. Certificates are issued in English and can be apostilled on request for use in international jurisdictions.