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20 results for “surface plasmon resonance”
Science · 8 August 2026
The Metal That Went Medical
…you had a virus. · Gold nanoparticles are red because collective electron oscillations — surface plasmons — absorb green light at around 520 nanometres. · The colour is size-dependent and aggregation-sensitive, which is what makes the particles usable as a readout rather than ju…
Amara Okonjo · 15 min read
Craft · 22 July 2026
Hallmarks and Assay: How Anyone Proves Gold Is Gold
…Fire assay remains the referee method; XRF is fast and non-destructive but reads only the surface. · Karat and fineness describe the same thing on different scales: 18ct is 750 parts per thousand gold. · Plating, filling and surface enrichment are the failure modes that surface-r…
Yusuf Demir · 12 min read
Industry · 7 August 2026
How Fake Gold Is Detected
…s. · XRF is fast, non-destructive and reads only the outer tens of microns — it validates surface composition, never the interior. · Ultrasonic velocity testing is the standard front-line defence against core-filled bars, because sound travels through tungsten far faster than thr…
Tomas Herrera · 15 min read
Industry · 4 August 2026
The Gold Inside Your Phone
…nding on the model and generation, spread across connector plating, printed-circuit-board surface finish, and the fine wires or bumps connecting silicon dies to their packages. At typical prices that is a few dollars of metal — negligible per unit, substantial across a billion un…
Tomas Herrera · 15 min read
Industry · 6 August 2026
The Scrap Trade
…gold; specialist refiners buying in volume pay far closer to it. · Handheld XRF reads the surface only, which is why plated and filled items are caught by density checks, file tests or a destructive assay. · Recycled gold is chemically identical to mined gold after refining — the…
Ingrid Sørensen · 15 min read
Craft · 5 June 2026
The Alchemy of Craft: What Goldsmiths Know That Machines Don't
…cific corner of a specific piece. Underheat and the metal stays brittle. Overheat and the surface begins to melt, leaving a pitted skin no amount of polishing will remove. Every experienced goldsmith has a ruined piece from the year they learned this. · The bench pin, the graver…
Yusuf Demir · 11 min read
Industry · 7 August 2026
After the Cyanide
…shape. Reagent circuits are rinsed and neutralised before the plant is stripped. Tailings surfaces are capped to exclude oxygen and shed water, or kept saturated to achieve the same end from the opposite direction, because both starve the sulphide oxidation reaction of what it ne…
Tomas Herrera · 17 min read
Industry · 2 July 2026
Nine Nines: Inside a Modern Gold Refinery
…, copper and lead convert to chlorides that either volatilise off as fume or float to the surface as a molten salt layer that can be skimmed. Silver becomes silver chloride and joins the skim. Gold, being the least reactive thing in the crucible, is left behind. · The operator's…
Tomas Herrera · 12 min read
Science · 9 August 2026
The Metallurgy of Karat
…ngle piece. It will be about fire scale, the dark copper-oxide layer that forms under the surface of copper-rich alloys during soldering and only reveals itself halfway through the final polish. · These are the properties that determine whether a design can be executed at all, an…
Tomas Herrera · 16 min read
Science · 10 August 2026
Where Gold Actually Comes From
…uch gold is in the Earth's core? Enough, by most estimates, to plate the entire planetary surface several metres deep — and utterly inaccessible. Gold is siderophile, meaning it dissolves preferentially into molten iron, so during core formation it followed the iron downwards and…
Tomas Herrera · 18 min read
Markets · 20 June 2026
Bring It Home: Central Banks and the Great Gold Repatriation
For half a century it was rational to store your gold in someone else's basement. Then the calculus of counterparty risk changed, and reserve managers started chartering aircraft. · Overseas custody w…
Ingrid Sørensen · 13 min read
Mining · 5 August 2026
Grade, Cut-off and the Arithmetic of an Open Pit
A gold mine is not a hole with gold in it. It is a spreadsheet with a hole attached — and the single number that decides which rock is ore and which rock is waste moves every time the price does. · Mo…
Amara Okonjo · 16 min read
Markets · 8 August 2026
Moving Bullion: The Logistics Nobody Prices
Between the vault and the buyer sits an industry of armoured vehicles, sealed cargo, bonded warehouses and insurance clauses. It rarely makes news, and it is the reason a spot price in London can dive…
Ingrid Sørensen · 17 min read
History · 14 July 2026
The Gold Standard: How a Soft Yellow Metal Became Money
For roughly five thousand years, humanity kept returning to the same element to settle its debts. The story is less about greed than about the unusually boring chemistry of atomic number 79. · Gold's…
Marguerite Adler · 14 min read
History · 9 August 2026
The Hoard Problem: What Buried Gold Actually Tells Us
A field of gold torcs and coins is a spectacular find and a treacherous document. The people who buried it were not writing to us, and the reasons they had for putting it in the ground are exactly wha…
Marguerite Adler · 16 min read
Mining · 22 May 2026
The Other Supply Chain: Artisanal Mining and the Mercury Problem
A significant share of the world's gold is produced by people working with hand tools, informal finance and a neurotoxin. Formalisation is the stated solution. Nobody agrees on what it costs. · Artisa…
Amara Okonjo · 12 min read
Craft · 3 August 2026
The Wedding-Season Bid: How Jewellery Demand Sets the Floor
Half the world's gold is worn, not stored. In India and China that distinction barely exists — and the buying behaviour it produces is the most reliably contrarian force in the entire market. · Jewell…
Yusuf Demir · 16 min read
Industry · 28 July 2026
Urban Mining: The Richest Gold Ore on Earth Is in Your Old Phone
A tonne of good underground ore holds a few grams of gold. A tonne of discarded circuit boards can hold two hundred. So why is most of it still going into landfill? · Concentration, not tonnage, is wh…
Tomas Herrera · 13 min read
Markets · 2 August 2026
Who Actually Sets the Gold Price
There is no single gold price. There is a London settlement number, a New York futures curve, a Shanghai premium and a jeweller's counter in Dubai — and the distance between them is where the market l…
Ingrid Sørensen · 15 min read
Markets · 6 August 2026
Why Central Banks Started Buying Gold Again
For three decades official institutions were net sellers of bullion, and the policy consensus treated the metal as a museum piece. Then, quietly, the world's reserve managers reversed. The reasons are…
Ingrid Sørensen · 17 min read
