Why Assaying Is Non-Negotiable
Gold's value is entirely dependent on its purity. A 1 kg parcel of gold at 85% purity is worth roughly $35,000 less than the same weight at 99.9% purity (at $3,300/oz spot). Assaying is the only way to know what you're buying.
The Four Main Assay Methods
1. Fire Assay (Cupellation)
The gold standard (literally) of assay methods. A sample is dissolved in acid, mixed with lead, and heated in a furnace. The lead oxidises, leaving pure gold. Accurate to ±0.01%.
Best for: High-value transactions, final settlement, refinery intake
2. XRF (X-Ray Fluorescence)
A non-destructive method using X-rays to identify elemental composition. Results in 30–60 seconds. Accurate to ±0.1–0.5%.
Best for: Rapid field screening, preliminary assessments
3. Acid Testing (Touchstone)
A traditional method using nitric and hydrochloric acid to determine approximate karat. Low cost, low precision.
Best for: Basic field verification only
4. ICP-OES (Inductively Coupled Plasma)
Highly accurate laboratory method that measures multiple elements simultaneously. Used for detecting base metal contaminants.
Best for: Complex alloys, detecting adulteration
Reading an Assay Certificate
A proper assay certificate includes:
- Sample reference number
- Gross weight and moisture content
- Gold content (% and g/t or troy oz)
- Silver and base metal content
- Testing laboratory name and accreditation
- Date and authorized signature
Protecting Yourself as a Buyer
- Always insist on an independent assay (not seller-provided)
- Split the sample — one portion for you, one for the seller
- Use SANAS, SGS, or Bureau Veritas accredited laboratories
- Request fire assay for any transaction over $50,000
Equator Gold Resources arranges independent SGS assay certificates for all shipments upon request.
Discuss Your Gold Sourcing Requirements
Interested in discussing legitimate gold sourcing, mining opportunities or African gold supply? Contact Equator Gold Resources to discuss your requirements and the applicable due-diligence process. Availability of gold is always subject to verification, and transactions are subject to applicable regulations.
About the Editorial Team
This article is published by the Equator Gold Resources Editorial Team for general educational purposes and does not constitute legal, tax, investment or professional advice. Gold transactions, mining, licensing, export, taxation, AML/KYC and documentation requirements differ by jurisdiction and change over time. Buyers and investors should confirm current requirements with the relevant government authorities in Uganda, the Democratic Republic of the Congo (DRC), South Sudan and other applicable jurisdictions, and seek advice from qualified legal, customs and assay professionals.
