Most writing on this subject is about spotting a fake: the magnet test, the ping, the scratch. Those checks catch crude counterfeits. They are not what a custody desk, an insurer or an institutional buyer relies on, and they say very little about the more realistic risk for a serious holder, which is a bar whose history cannot be established. The professional market answers the question “is this bar real?” with several separate kinds of evidence, each designed for a different failure. Understanding which is which is more useful than any single test.
How do you check a gold bar's serial number and assay card?
Start by confirming that the bar's stamped marks, including refiner name or logo, fineness, weight and serial number, match the assay card and the refiner's published format for that product. Where the refiner offers a certificate lookup or scanning tool, use it. Treat a match as consistency, not proof: it shows the bar and paperwork agree, not that the bar is the one the refiner originally made.
A bar's marks are its identity. Large wholesale bars carry the refiner's mark, fineness, year and a serial number, and smaller retail bars usually carry a comparable set. The assay card, where one is issued, is the refiner's written statement of weight and fineness for that specific serial number, often sealed together with the bar in tamper-evident packaging.
A small number of refiners go further, with scanning apps such as VERISCAN, which compare a bar's microscopic surface profile, captured on the production line, with a registered record for that refiner's enrolled products. That is a stronger check than reading a number, because it tests the physical object rather than the label. It is also refiner-specific: it works only for that refiner's enrolled products, and most bars in circulation have no equivalent.
Hence the limit, stated plainly. A serial number proves that a number exists. A lookup, where one exists, proves that the refiner issued that number. Neither proves that the object carrying the number is the object the refiner made, because marks, cards and packaging are the parts a counterfeiter copies first. The paperwork is the start of the question, not the end of it.
What can an owner actually verify about a specific bar, and what can't they?
An owner can check marks, weight and dimensions against the refiner's specification, and can pay for surface analysis and ultrasonic testing. What an owner generally cannot establish alone is the bar's full interior composition without destroying it, or its history before it arrived.
Each common method reads one physical property, and each has a known blind spot:
- Visual, weight and dimension checks catch sloppy fakes. They are weak against tungsten, the counterfeiter's metal of choice, because its density of roughly 19.25 g/cm³ sits within about a quarter of a percent of gold's 19.30 g/cm³, a gap described in a 2021 comparative review of non-destructive gold testing as too small for common field instruments to resolve reliably.
- X-ray fluorescence (XRF) gives an accurate reading of surface chemistry, but, as the instrument maker Evident notes in its bullion application guidance, portable XRF is limited to the surface being analyzed. A gold skin over a tungsten core can read as fine gold.
- Ultrasonic testing sends sound pulses through the bar and looks for echoes from internal boundaries, such as an insert or void. Evident describes pairing it with XRF so the surface reading can be treated as representative of the whole bar. It requires a calibrated reference and an operator who knows what a known-good bar of that type looks like.
- Fire assay remains the destructive reference method for fineness. It is definitive for the sample taken, and it consumes metal, which is why nobody applies it to a bar they intend to keep.
The honest conclusion is that owner-level testing reduces risk rather than removing it. Combining independent methods narrows the gap considerably, and a clean result from a qualified tester is meaningful. But the reason professionals rarely need to test at all is not that they have better instruments. It is that they rely on the next two layers.
What does LBMA Good Delivery actually certify?
Good Delivery certifies refiners, not bars in your possession. The LBMA accredits refiners whose large bars meet its specification and keeps them under continuing supervision; only bars from those refiners, meeting that specification, can settle a Loco London contract.
We cover what Good Delivery is and why the refiner matters in our Beyond Retail guide to custody standards. The detail worth adding here is what it takes to get on the List and stay on it, because that is where the credential's value comes from.
According to LBMA's application criteria, an applicant is unlikely to be viewed favorably unless it has existed for at least five years, has refined the relevant metal for at least three, produces at least 10 tonnes of gold (or 50 tonnes of silver) a year, holds tangible net worth of at least £15 million, passes the ownership and reputation due diligence practiced in the London market, and implements LBMA's Responsible Sourcing Programme. Applicants then pass an assay test and have their own bars tested.
Staying on is not automatic. The Good Delivery Rules review each refiner's throughput and net worth on a three-year moving average, with a watch list and remedial plans for those that fall short, alongside continuous monitoring of production and an annual third-party responsible-sourcing audit. Refiners can be suspended or moved to the Former List.
Two limits follow. First, the standard covers large wholesale bars; LBMA's Good Delivery FAQs state that kilobars, 100-ounce and smaller bars are not acceptable in the London wholesale market, even when a listed refiner made them. A retail bar from a listed refiner inherits the maker's reputation, not the wholesale standard. Second, the credential says who made the bar and to what specification. It is silent on everything that happened after the bar left the refinery.
What is the “chain of integrity,” and what happens when a bar leaves it?
The chain of integrity is the unbroken, recorded custody of a bar from an accredited refiner through recognized vaults and carriers. While it holds, professional buyers accept the bar at face value without re-testing. When it breaks, the bar has to prove itself again, usually at the seller's cost.
This is the layer the other checks depend on. A wholesale bar that has moved only between recognized vaults, with a movement record at each step, does not need to be re-examined by every new holder, because every hand it passed through was accountable for it. LBMA's own guidance on non-destructive testing states the position directly: there is no definitive non-destructive testing solution the market can endorse, so the best risk mitigation of sub-standard assay remains the Good Delivery eco-system of refineries and chain of custody. Staying inside professional custody is not a formality. It is the accepted substitute for re-testing, and it is why a bar inside the chain trades on its record rather than on a fresh assay.
The stakes are not hypothetical. In 2019, Reuters reported that kilobars carrying the stamps of major Swiss refineries — but not produced by them — had been identified by all four of Switzerland's leading refiners and found in the vault of one of the bullion market's largest banks. The gold in those bars was real and high-purity; the marks were forged. At least a thousand such bars, worth a combined $50 million or more, had surfaced in three years, with thousands more possibly undetected.
Nor is this a problem that went away after the 2010s. In 2024, Indonesia's Attorney General's Office named six suspects in a case involving roughly 109 tonnes of gold bars sold under the brand of the state refiner Antam between 2010 and 2021 (Tempo, May 2024). Officials were careful to state that the metal itself was genuine; the failure was the brand — the Antam mark had been applied to bars that never went through the refiner's sanctioned process, and buyers were left unable to tell which bars carried a legitimate mark and which did not, prompting what local reporting described as a crisis of confidence among Antam's own customers(The Jakarta Post, June 2024). In every one of these cases the gold passed surface inspection, carried a plausible mark and arrived with the buyer expecting paperwork to settle the question — and the paperwork was the problem.
What happens when a bar leaves the chain follows from all of this. A professional buyer can no longer take the bar at face value, so it must be re-verified before any bid — testing, transport and insurance at the seller's cost and on the seller's timeline — and where the result still does not satisfy the buyer, the bar may have to be melted and recast by a refiner before it is marketable again. None of this implies the bar is fake. It means nobody can vouch for it any more, and the market prices that uncertainty in delay, cost and, ultimately, a lower bid.
For retail coins and small bars, the same principle applies in a softer form: sealed original packaging, purchase records and documented storage all shorten the conversation when it is time to sell.
What is the Gold Bar Integrity Programme, and how is it different from a serial number?
It is the market's attempt to digitize the chain of integrity. In its current, live form it is an LBMA database built with aXedras on distributed-ledger technology that collects governed data from refiners and London vaults. It records provenance and reporting information, not ownership, and it is not a public lookup for an individual bar.
The history matters, because much coverage still describes the original plan as if it were the current system. In March 2022, LBMA and the World Gold Council announced a pilot with two ledger vendors, aXedras and Peer Ledger, describing an eventual goal of registering and tracking bars from mine to vault and beyond. That was a vision statement for a pilot, not a description of a working system.
What went live is narrower and more practical. LBMA launched the GBI Database in January 2025, powered by aXedras, focused initially on two datasets: refiner data, such as responsible-sourcing deliverables and country-of-origin information, and London vault holdings. LBMA's 2025 annual report states that all Good Delivery refiners have been onboarded and have submitted their responsible-sourcing documents through the platform, that London custodian onboarding is progressing toward 100 percent, and that aggregated vault-holdings reporting through the platform is expected by the end of 2026. A February 2026 update added voluntary periodic country-of-origin reporting from April 2026, moving to mandatory monthly reporting in 2027.
So, as of this review: live for refiner data, in progress for London vaults, and still a stated goal rather than a working reality for bar-by-bar tracking through the whole chain. LBMA separately accredits physical security features that act as a bar's “passport,” described on its Gold Bar Integrity Ecosystem page, but that is a distinct component from the database.
Two distinctions are worth holding firmly. First, a ledger record is not the same thing as a serial number. A serial number is stamped on the object and can be copied; a governed record captures who submitted what, when, under whose oversight, and is only as reliable as the institutions feeding it. Second, this is not tokenization. Nothing is issued to investors, nothing trades, and an entry in the database is not ownership of gold or of a digital asset. It is provenance infrastructure for the market's own supervision.
The four layers side by side
| Layer | Question it answers | What it shows | What it doesn't |
|---|---|---|---|
| Individual bar checks | Does this object match what it claims to be? | Marks, weight, dimensions and surface composition are consistent with the stated bar; ultrasonic testing can reveal internal insertions. | Prove the interior is pure by itself, or say anything about where the bar has been. |
| Refiner accreditation (Good Delivery) | Is the maker a recognized, continuously supervised producer? | The refiner met LBMA's entry criteria and remains subject to ongoing monitoring and responsible-sourcing audits. | Verify any single bar after production, or endorse the dealer, vault or insurer. |
| Chain of integrity | Has the bar stayed inside professional custody since it was made? | A continuous, recorded movement from accredited refiner to recognized vaults, so buyers can accept it without re-testing. | Survive a break. Once the bar leaves, the record no longer vouches for it. |
| Gold Bar Integrity database | What does the market's central record show about origin and holdings? | That refiners have submitted governed provenance and responsible-sourcing data to LBMA through a permissioned ledger. | Act as a public lookup for your bar, confer ownership, or replace physical verification. |
Does any of this guarantee a bar is genuine?
No. Each layer reduces a specific risk, and together they make a counterfeit much harder to introduce and much easier to catch. None of them, alone or combined, is a guarantee, and none of them has anything to do with what the gold will be worth.
The layers are complementary precisely because each fails differently. A perfect assay card attached to a filled bar fails at the physical layer. A genuine bar from an accredited refiner that sat in an unrecorded location for years fails at the custody layer. A clean database record for a refiner says nothing about a bar that was swapped after it left. Treating “LBMA-listed,” “has a serial number,” “in the chain” and “on the ledger” as one idea is the most common mistake in this subject, and it is the one that costs money.
It also bears repeating that authenticity is a separate question from value. A verified bar is exposed to the gold price in exactly the same way as any other. Verification protects against owning the wrong object, not against price movement.
How does this connect to how Dormy structures custody?
We treat verification as a structural question answered before purchase: documented product origin, custody arrangements that preserve the record, and paperwork that identifies what was received. The goal is that a client should never need to prove a bar's history after the fact.
In practice that means sourcing product whose refiner or mint of origin is documented, keeping metal inside professional depository custody where the intake and movement record stays intact, and making sure statements identify holdings specifically enough to reconcile. For IRA-owned metal, depository custody is required anyway, as our Gold IRA guide explains. For direct ownership, the choice is the client's, and we are explicit about what home storage does to the custody record when it is time to sell. The standards behind this, including allocated ownership as the one non-negotiable, are set out on our Beyond Retail page.
Related reading
- Gold bars vs. coins
- Gold IRA or buying gold outright
- The home-storage Gold IRA myth
- Physical gold vs. gold ETFs
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