Assay / Assay Certificate
Also: Assay Card, Bar Certificate, Certificate of Assay, Inspection Certificate
An assay certificate is an authenticity document issued by an accredited testing laboratory that officially confirms the fineness, weight, and identity of a precious metal bar.
An assay certificate (also known as Certificate of Assay or Assay Card) is a document issued by an independent, accredited testing laboratory or by the manufacturer itself that is permanently associated with a precious metal bar. It officially confirms that the bar in question possesses the stated properties – in particular fineness, gross weight, fine weight, and serial number. For buyers, the certificate is the most important instrument of authenticity verification short of a full chemical analysis.
How an Assay Certificate is Created
After a bar has been cast or minted, the refinery or a commissioned laboratory takes a material sample and analyses it. Common methods include:
- Fire assay (cupellation): Classic wet-chemical method, regarded as the reference procedure for gold and silver.
- X-ray fluorescence analysis (XRF): Non-contact spectral analysis, fast and non-destructive.
- Flame atomic absorption spectrometry (FAAS): High-precision method for trace elements and alloy components.
The result is recorded on the certificate and assigned to an individual serial number that is engraved or stamped on the bar.
Structure of an Assay Certificate
| Required Information | Example |
|---|---|
| Manufacturer / Testing Laboratory | PAMP Suisse, Heraeus, Valcambi |
| Bar Number (Serial Number) | 00412857 |
| Metal | Gold (Au) |
| Gross Weight | 31.103 g (1 troy ounce) |
| Fineness | 999.9/1000 |
| Fine Weight | 31.100 g |
| Testing Date | 2026-07-23 |
| Stamp / Signature of Testing Laboratory | Embossing or hologram |
Assay Card Bars in Blister Packaging
The most common way to permanently link an assay certificate to a bar is the so-called blister pack (also Assay Card Packaging): the bar and certificate are sealed together in a transparent plastic enclosure. As long as the blister is unopened and undamaged, the bar contained within is considered certified and untouched. A broken or damaged blister generally reduces the dealer buyback price, because the association between bar and certificate can no longer be established beyond doubt.
Assay Certificate vs. LBMA Good Delivery
The LBMA Good Delivery label is not an individual certificate for each bar, but rather an accreditation for the manufacturer and its production process. A Good Delivery bar (400-troy-ounce standard bar for institutional trading) carries stamps with a serial number and fineness, but no accompanying Assay Card. The assay certificate as a physical accompanying document is primarily relevant for small bars (1 g to 1 kg) in the retail segment.
Practical Value When Buying and Reselling
When buying gold, the assay certificate offers three concrete advantages:
- Immediate authenticity verification without your own testing equipment – the serial number on the bar must match the certificate.
- Better resale conditions – dealers typically accept certified bars in original blister packaging without a surcharge for re-testing; uncertified material often incurs a deduction from the melt value.
- Documentation for inheritance and insurance – the certificate serves as proof of the identity and value of the bar.
The melt value of a bar can be calculated at any time independently of the certificate, based on the current gold price and the stated fine weight.
In Brief
An assay certificate builds trust through verifiable provenance: it links a specific bar via its serial number to an independent verification of fineness and weight. When buying small bars, the blister should always remain unopened to preserve the full documentation value. For tax or investment advisory questions regarding resale, please consult a qualified adviser.