A one ounce coin has travelled a long way before it reaches a display case. Understanding that journey explains several things buyers ask about, including why refiner names matter and why a premium exists at all.
Mining and concentration
Gold occurs in very low concentrations. Economically viable ore commonly contains only a few grams of gold per tonne of rock, which means enormous quantities of material are moved to produce a modest amount of metal.
Ore is crushed and ground, then the gold is separated using chemical and physical processes. The output is a concentrate rather than anything resembling finished metal.
Doré bars
At the mine site, concentrated material is smelted into doré, a semi pure alloy typically cast into rough bars.
Doré is not bullion. Purity varies considerably, commonly somewhere between 60 and 90 percent gold, with silver and base metals making up the rest. It is simply a convenient and secure form in which to ship value from a mine to a refinery.
Refining
Refineries take doré and separate the gold from everything else. Two processes dominate.
The Miller process uses chlorine gas passed through molten gold. Base metals and silver form chlorides that separate out. It is fast and produces gold of roughly 99.5 percent purity, which is enough for many industrial uses but short of bullion standard.
The Wohlwill process uses electrolysis. Impure gold is used as an anode in an acid electrolyte, and pure gold deposits on the cathode. It is slower and ties up more capital in metal, but reaches 99.99 percent and above.
Many refineries run Miller first to remove the bulk of impurities, then Wohlwill to reach bullion purity. Silver and other metals recovered along the way are refined separately, which is one reason silver often arrives as a by product of gold and base metal mining.
Accreditation
Refineries producing large bars for institutional trade are accredited under the LBMA Good Delivery List, the internationally recognised standard for the wholesale market. Accreditation covers assay accuracy, bar quality and the refiner's financial standing.
That accreditation is why a refiner's name carries weight. It represents an audited, ongoing standard rather than a claim the refiner makes about itself. Our article on how the gold price is set covers the wholesale market this feeds.
From wholesale bar to retail product
Wholesale bars are far too large for retail buyers, so metal is worked into consumer products.
Cast bars are made by pouring molten metal into moulds and stamping the result. Simple, quick, and the cheapest route.
Minted bars are made by rolling metal into sheet of precise thickness, punching out blanks, and striking them under pressure. More steps, more equipment, better finish.
Coins follow the minted bar process with more stages. Blanks are annealed to soften them, cleaned, given a raised rim, then struck with the design, often more than once. Sovereign mints add quality control and frequently security features.
Each stage adds cost, which is the concrete reason a struck coin carries a higher premium than a poured bar containing identical metal.
Assay and packaging
Finished products are verified for weight and purity, and minted bars are commonly sealed into assay cards carrying a serial number matching the bar. That packaging is part of the verification chain, which is why keeping it sealed matters.
Frequently asked questions
What is a dore bar?
A semi pure alloy bar cast at a mine site, typically 60 to 90 percent gold, produced as a secure way to ship value to a refinery. It is not bullion.
How is gold refined to 9999 purity?
Usually by the Wohlwill electrolytic process, often after the Miller chlorination process has removed the bulk of impurities.
How much ore does one ounce of gold take?
Economically viable ore often contains only a few grams per tonne, so producing a single ounce can require moving several tonnes of rock.
Why do coins cost more than bars?
More production stages. Rolling, blanking, annealing, rimming and striking each add cost that pouring a cast bar avoids.
What does LBMA accreditation mean?
That a refinery meets audited international standards for assay accuracy, bar quality and financial standing, and appears on the Good Delivery List.
Browse the range
We stock products from accredited refiners and sovereign mints. See the range or visit the showroom at 124 Peterborough Street, Christchurch.