How Labs Detect Fake Gold in Nigerian Markets

In busy trading hubs—from Lagos Island to Kano—gold changes hands every day. With prices high and margins tight, counterfeiters mix brass, plate base metals, or even hide tungsten cores inside bars. Nigerian buyers now lean on laboratory testing to separate real value from clever fakes. Here’s how labs do it, what each method catches (and misses), and smart tips for retailers and consumers.

The quick screen: XRF tells the metal story (non-destructive)

Most labs begin with X-ray fluorescence (XRF). The analyzer fires X-rays at the item and reads the “fluorescent” energies emitted by its atoms—an elemental fingerprint. In seconds, you see the percentages of Au, Ag, Cu, Ni, Zn and more, which exposes low-karat alloys and gold-plated brass. XRF can also flag hidden base metals beneath thin plating, though it mainly reads the surface to shallow .

Where it shines: grading karat, catching plated pieces, checking if a “24K” chain is really 58.5% Au (14K).
Limits: deeply buried cores (e.g., thick gold over tungsten) may require deeper-probe tests.

The classic check: acid/touchstone tests (fast, low cost)

Assayers still use nitric-acid touchstone kits for shop-floor verification. A streak from the item is compared against known karat needles; how the streaks react to acid indicates karat (or a fake). It’s cheap and fast—but gives only an estimate and can be fooled by clever plating. gia.edu+1

Pro tip: use verified karat needles and compare side-by-side; reserve aqua regia only for controlled lab work.

Density & specific-gravity: catching the obvious…and the crafty

Real gold’s density (~19.32 g/cm³) makes specific-gravity tests powerful for coins, bars, and heavy jewelry. Many fakes are lighter; however, counterfeiters sometimes choose tungsten (density ~19.25 g/cm³), which mimics gold by weight—so density alone is not enough. Use it alongside XRF. The Safe House SG

When scammers go deep: ultrasonic & advanced checks

To defeat tungsten-filled bars or hollow pieces with gold skins, labs add ultrasonic testing. Sound travels at different speeds through gold vs. tungsten, so pulse-echo instruments reveal internal layers or voids. Research shows ultrasound detects tungsten-cored bars that XRF (a surface method) might miss. Electrical-conductivity checks and acoustic “ring” tests can support the finding.

Hallmarks, paperwork, and Nigerian oversight

Authenticity also lives on the stamp and the certificate. Hallmarking—stamping purity and the assay office mark—protects buyers globally, and Nigerian consumers benefit when imports and locally sold jewelry carry recognized marks with assay documentation. Standards Organisation of Nigeria (SON) leads quality assurance; traders who align with recognized standards and provide test reports build trust and avoid seizures. White Gold+1

(Note: Minimum legal karats vary by market; training materials used in Nigeria reference 9K+ thresholds for gold and 92.5% for silver—buyers should verify marks against documentation, not marks alone.)

A lab’s step-by-step workflow

Visual & magnet check – look for base-metal seams, poor plating, and (rarely) magnetic response.
XRF scan – quantify composition for karat and alloying metals.
Specific gravity – verify weight-to-volume consistency.
Ultrasonic/EC tests – rule out tungsten cores or hollow builds.
Documentation review – hallmark/certificates cross-checked with invoices and assay reports.
(If needed) wet chemistry or fire assay – destructive, but definitive for disputes.

Buyer checklist for Nigerian markets

Ask for an XRF printout with karat and alloy percentages; keep it with your receipt.
Don’t rely on one test. Pair density with XRF; add ultrasound for thick pieces and bars.
Verify marks, not just shine. Hallmarks plus paperwork beat “word of mouth.”
Be wary of “too-good” prices and mixed-metal clasps on “24K” items.
Use accredited labs or jewelers who calibrate equipment and can show QA records.

Bottom line

Counterfeiters evolve—but so do Nigerian labs. By combining XRF for composition, specific-gravity for physics, and ultrasonic/EC for hidden cores, professionals can authenticate gold quickly and defensibly. For traders and consumers, insisting on documented tests is the surest way to turn a good deal into a good asset—not a costly lesson.

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