The Gold & Precious Metals Handbook

I Foreword: The Other Half of the Ring

Anna, our FGAA-qualified gemmologist, on the half of every piece of jewellery that buyers research least and wear most — and why the metal, not the stone, is usually the part that fails first.

People arrive at my bench in Sydney extraordinarily well prepared about the stone. They have read about heat treatment and origin reports, they know what a windowed pavilion looks like, they have opinions about Ceylon versus Madagascar, and they can tell me why they want an unheated sapphire rather than a heated one. Then I ask what metal they would like it set in, and there is a pause, and somebody says "gold, I suppose — white?" That pause is what this book is about.

It is not a criticism. The stone is the romantic part and the metal feels like packaging, the way the frame feels secondary to the painting. But the metal is not packaging. It is the structural component of the object. It is the part that bends when you catch it on a car door, thins where it rubs against a wedding band, discolours where your skin chemistry is unkind, loses its bright finish on a schedule nobody quoted you, and — in the failure I see most often and hate most — wears through at a prong until a stone you chose carefully falls into a car park and is never seen again. In more than a decade of looking at damaged jewellery, I have lost count of the stones lost to worn metal. I can count on one hand the stones lost because the stone itself failed.

Three questions, every single week

There are three questions that arrive at the counter with such regularity that I could set my watch by them, and they are the spine of this handbook. The first is why is my white gold ring turning yellow? — asked in the tone of somebody who suspects they have been sold something fake. They have not. The answer is in Chapter IV, and it involves the fact that white gold is not white and never has been. The second is is 9ct better for everyday wear than 18ct?, which is the most repeated claim in Australian retail and, on the published hardness figures, largely backwards. That is Chapter III. The third is what is vermeil, exactly?, usually asked by somebody who has just spent a few hundred dollars on a chain and would like to know what they own. Chapter VI answers it, along with the five other rungs of the ladder that runs from solid karat gold down to a word that means nothing at all.

The gap Australia leaves open

There is a structural reason these questions are so hard for a buyer here to settle. Australia has no government assay offices and no compulsory hallmarking law. The number stamped inside your ring was applied by whoever made it, not by an independent tester with a statutory obligation. In Britain, an article of gold over one gram cannot legally be sold without being assayed first. In India, since 1 April 2023, a hallmarked piece must carry a six-character identity code you can check on your phone. In Australia, the protection you actually have is the Australian Consumer Law's prohibition on misleading or deceptive conduct, which applies to consumer purchases from Australian sellers and works after the fact rather than before it. The Australian Competition and Consumer Commission's own 2005 jewellery publication documented items sold as gold that carried less than one per cent gold content. That is not a reason for alarm. It is a reason to test the metal rather than read the stamp and hope, and Chapter VII shows you how.

How this volume is built

Every figure in the pages that follow is traceable to a named source, and I have put the names in the prose rather than burying them: CIBJO's Precious Metals Blue Book for fineness, the Chard hardness tables for the 9ct argument, the United States Federal Trade Commission's Jewelry Guides at 16 CFR Part 23 for the plating definitions, the Edinburgh Assay Office and the Bureau of Indian Standards for hallmarking, the Gemological Institute of America for cleaning, Chemistry World for why silver goes black, the National Council of Jewellery Valuers for valuation, and market data from Trading Economics and JM Bullion for the spot prices, each with the date it was read. Where a number is a trade estimate rather than a measurement — the retail markup figures in Chapter IX are the clearest case — I say so in the same sentence. Where the trade genuinely disagrees with itself, as it does about how long rhodium plating lasts, I give you both numbers and the honest range between them instead of picking whichever suits a sale.

I should also say plainly what we sell, because you are entitled to weigh it. Ministry of Gems is a coloured-stone house. We sell gems and we make jewellery around them; we do not sell plated fashion chains, and I have no commission riding on whether you choose 9ct or 18ct or platinum. That independence has limits and you should assume I have blind spots like anyone else, which is why the numbers are sourced — so that you can check me rather than trust me.

One last thing before we begin. Nothing in this handbook is snobbery about cheaper metal. Gold-plated jewellery, vermeil and 9ct all have a legitimate place, and a well-made plated chain honestly described as a plated chain is a perfectly good product that a great many people should buy. What I object to is not the product. It is the description — the vermeil sold as though it were solid, the 9ct sold with a durability story that the metallurgy does not support, the rhodium cycle that nobody mentions until the ring goes yellow at eighteen months. Buy any rung of the ladder you like. Just buy it knowing which rung you are standing on.

— Anna, FGAA
Ministry of Gems, Sydney

II Karat, Fineness and the Physics of Softness

What 375, 585, 750, 916 and 999 actually mean, why pure gold is too soft to hold a stone, and how Henry VIII settled the durability argument in 1526.

Karat is a fraction and nothing more mysterious than that: parts of gold out of twenty-four, measured by mass. Eighteen karat is eighteen parts gold and six parts something else, which is seventy-five per cent, which is why the same metal is stamped 750 in the millesimal system — parts of gold per thousand. The two notations describe one number in two dialects. Nine karat is 9/24, which is 37.5 per cent, stamped 375. Fourteen karat is 585, twenty-two karat is 916 and twenty-four karat is 999. Learn those five numbers and you can read the inside of almost any ring in the world.

The fineness ladder, and the one that is rounded

CIBJO — the World Jewellery Confederation — sets out the recognised fineness steps in its Precious Metals Blue Book: 999, 986, 916, 750, 585, 416, 375 and 333. That is the international vocabulary, and it is worth noticing what CIBJO does not allow. There is no negative tolerance at all. An article may not assay below the fineness it declares, not by a fraction. If it says 750 it must be 750 or better. Some national systems are more forgiving; the American stamping law permits a small shortfall, which I come to in Chapter VI. The CIBJO position is the strict one and it is the standard a serious maker works to.

One entry on that ladder is a rounding decision rather than a fraction. Fourteen twenty-fourths is 58.333 per cent, so the honest mark would be 583, and that is exactly what the Soviet system used. International convention rounds up to 585, which means a piece marked 585 must contain slightly more gold than fourteen karat strictly requires. Russia moved from 583 to 585 in the early 1990s to harmonise with international trade, which is why an old Soviet-era ring can carry a mark that looks wrong to a modern eye and is entirely genuine. If you inherit something stamped 583, you have not been cheated by two parts per thousand. You have a piece with a history.

Why pure gold is the wrong material for a prong

Here is the fact that governs everything else in this book. Pure gold is beautiful, it is chemically almost inert, it will never tarnish, and it is nearly useless as a structural material for Western fine jewellery. Annealed 24 karat gold measures roughly 20 to 30 on the Vickers hardness scale, with a yield strength somewhere around 40 to 50 megapascals — which in plain language means it deforms permanently under ordinary handling. On the Mohs scale gold sits at 2.5 to 3, which puts it at about the hardness of a fingernail. A pure gold ring worn daily will go oval. A pure gold prong will bend away from the stone it is holding the first time you knock it against a bench.

The fix is alloying. Adding copper, silver, palladium or zinc introduces atoms of a different size into the gold's crystal lattice, and those mismatched atoms obstruct the planes along which the metal would otherwise slide. Metallurgically that obstruction is the whole story of hardness, and the effect is dramatic: a well-chosen alloy can be five to six times harder than the pure metal it started as. This is why fine jewellery is made from alloys rather than fine gold, and why the number stamped inside your ring is a compromise being struck on your behalf between how much gold you own and how well the object survives being worn.

Henry VIII settles it in 1526

The compromise is not new. In 1526 Henry VIII set the English coinage standard for gold at 91.67 per cent — twenty-two parts in twenty-four — and the reason was not economy but wear. Coins of higher fineness abraded away too quickly as they passed from hand to hand, and a currency that loses mass in circulation is a currency that loses value. The standard he set became known as crown gold, and the Royal Mint still strikes sovereigns to that same 916.7 fineness five centuries later. When a modern jeweller tells you that 22 karat is too soft for a delicate setting, that jeweller is repeating a conclusion a Tudor mint master reached about pocket change.

The numbers bear it out. On the Chard hardness tables, 22 carat gold manages only about 50 to 90 Vickers, and annealed 22K alloys can sit as low as 50 to 70 against 120 to 200 for typical 18 karat alloys. That is a metal you can work beautifully and a metal that will not hold a thin claw over a lifetime of wear.

What the high-karat world knows that we do not

It would be provincial to leave it there, because a very large part of the world's jewellery is made in 22 and 24 karat and does not fall apart. South Asian and Chinese high-karat traditions — the 916 standard of Indian goldsmithing, the chuk kam gold of the Chinese trade — solve softness by design rather than by alloying. They use heavier sections, closed and bezel-set forms rather than exposed prongs, and work-hardening at the bench. Research published in the metallurgical literature and summarised by Ganoksin has produced genuinely hardenable high-karat alloys, and specialist makers sell daily-worn 22 and 24 karat pieces on exactly that basis. The honest position, then, is narrower than the usual Western claim. Pure and near-pure gold is unsuited to prong-set Western fine jewellery. It is not unsuited to jewellery as such, and a 22 karat bangle from Chennai is not a naive object — it is a different engineering solution to the same problem.

For a stone in a claw setting, though, the physics is unforgiving, and it is why almost everything we make sits at 18 karat, 14 karat or platinum. The gold content you can see on the invoice matters. The gold content that keeps a sapphire in its seat for forty years matters more.

III The 9ct Question

Australian counters have been telling buyers for generations that 9ct wears better than 18ct. The published hardness figures say something more complicated, and the honest answer changes what you should buy.

If you walk into ten jewellers in this country and ask which gold is best for a ring you will never take off, a good number of them will tell you 9ct, because it is harder. It is the most durable piece of retail folklore in the Commonwealth, it is repeated in complete good faith by people who were taught it by people who were taught it, and it survives because it contains just enough truth to be difficult to kill. It is also, as a general statement about wear, largely backwards.

What the hardness tables actually say

The most useful published figures I know are the alloy hardness tables maintained by Chard, the long-established British bullion dealer, which give Vickers numbers by karat and by temper. As cast, 9 carat gold runs about 70 to 105 Vickers and can be hardened to somewhere near 160 to 170. As cast, 18 carat runs 85 to 125 — already higher — and properly age-hardened 18 carat alloys reach 170 to 230. Fourteen carat, interestingly, is the quiet overachiever: 125 to 165 as cast, 150 to 180 hardened, which makes it the hardest of the three straight out of the mould. And 22 carat, as we saw in the last chapter, manages only about 50 to 90.

Read those numbers plainly and the retail claim inverts. A properly processed 18 carat ring is usually the harder object as well as the more valuable one, and a 14 carat ring is harder still in the as-cast state most jewellery is actually finished in. The temper matters enormously — the same alloy can nearly double in hardness depending on how it was heat-treated after casting — which is precisely why sources appear to contradict one another. A guide comparing as-cast 9ct against as-cast 18ct will find a small difference. A guide comparing work-hardened 9ct against annealed 18ct will find a large one in the wrong direction. Most retail folklore is built on that second, unfair comparison.

Where the half-truth lives

There is a real property underneath the myth, and it deserves saying properly, because a buyer who is told the whole thing is nonsense will rightly distrust the correction. Hardness is resistance to being scratched or indented. Stiffness is resistance to being bent. Toughness is resistance to being broken. They are three different properties, and glass is the standard classroom illustration: harder than rubber and vastly less tough. In certain tempers, 9 carat alloys are stiffer and springier than the equivalent 18 carat — a thin 9ct shank will resist going out of round in a way that a soft 18ct shank will not. Bench jewellers feel this and are not imagining it. What they are generalising from is a particular property in a particular temper, and what they are leaving out is everything in the next paragraph.

The other 62.5 per cent

Nine carat gold is 37.5 per cent gold. The remaining 62.5 per cent is copper, silver, zinc and sometimes nickel — mostly base metal, and base metal behaves like base metal. It reacts with skin, with perfume, with the sulfur in the air and with chlorine. Nine carat discolours where 18 carat barely marks; it is the alloy I most often see with a dull grey-brown film in the recesses of a carved shank. It is also the most vulnerable of the common gold alloys to the chlorine stress-corrosion problem in Chapter IX, for the simple reason that there is more base metal available to be attacked and less gold shielding it. If you swim daily in a chlorinated pool wearing a 9ct ring, you are running a slow experiment on your own prongs.

Then there is what you own. Melt value is weight times fineness times spot price, and nothing else. With gold at roughly A$6,410 an ounce — the Australian-dollar figure quoted by Melbourne Gold Company on 21 August 2026 — fine gold works out near A$206 a gram. One gram of 18 carat contains 0.75 grams of fine gold, so about A$154 of metal. One gram of 9 carat contains 0.375 grams, so about A$77. Same weight of jewellery, half the gold, and that gap does not close over time. It is the honest reason 9ct exists, and it is a perfectly respectable one.

What I actually recommend

For a ring worn every day, 18 carat if the budget reaches it: the best combination of hardened durability, colour stability and retained value, and the standard we use for most of our made-to-order work. Fourteen carat is an excellent middle and is under-sold in Australia compared with the United States — harder as cast than either neighbour, meaningfully more gold than 9ct, noticeably cheaper than 18ct, and a sensible answer for someone hard on their hands. Nine carat when the budget rules, chosen with open eyes for what it is: a cost decision, not a durability upgrade. And if a salesperson offers you the durability story, you now have the Chard numbers to ask about temper, which is a question they will not be expecting.

One caveat that cuts the other way. If a piece will be repaired, resized and re-tipped many times over a long life — an heirloom in constant circulation, say — the lower melting point and easier working of 9ct genuinely makes a bench jeweller's life simpler and the repair bill smaller. That is a real argument for 9ct. It is just not the argument that gets made.

IV Colour Is Chemistry: Yellow, Rose and the White Gold That Isn't White

Copper makes rose, nickel and palladium make white, and no white gold on Earth is actually white — which is why your ring is turning yellow, and why that is not tarnish.

Gold has one colour. Every other colour you have ever seen on a jeweller's tray is a recipe, and once you know the recipes you can predict how a piece will behave before you buy it. Colour in karat gold is not a coating or a finish or a marketing name. It is the alloy, and the alloy determines the hardness, the skin reaction, the tarnish behaviour and the maintenance schedule as surely as it determines the hue.

Yellow, and the balancing act inside it

Yellow gold alloys balance silver and copper around the gold. Silver pushes the colour greenish and pale; copper pushes it warm and red; the classic yellow is the point where the two cancel and you get something close to the colour of pure gold at a workable hardness. Because the balance is a choice, 18 carat yellow from two different makers can read visibly differently side by side — one buttery, one brassy — and neither is wrong. This matters practically when you are matching a new ring to an inherited one, or ordering a wedding band to sit against an engagement ring made a decade earlier by somebody else. Bring the old piece. Colour-match by eye, in daylight, at the bench. It is not something you can specify by number.

Rose is copper, and lower karat is redder

Rose gold is gold plus copper with a little silver, and the International Gem Society's figures put 18 karat rose at roughly 75 per cent gold, 22 to 25 per cent copper and 2 to 3 per cent silver. Fourteen karat rose is about 58.3 per cent gold with over 40 per cent copper. That is the whole explanation for something buyers find counterintuitive: lower-karat rose gold is redder, because with less gold in the mix there is proportionally more copper doing the colouring. A 9ct rose ring will be distinctly more coppery than an 18ct one, and if you are matching pieces across karats, they will not match.

The copper brings a bonus and a cost. It hardens the alloy, so rose gold is generally the toughest of the three colours at any given karat. It also oxidises, so rose gold darkens gently with age into a warmer, slightly deeper tone. Many people, myself included, find that patina lovely; it is the closest gold comes to the way silver ages. If you want it bright, it polishes back in minutes. Just know that it is normal and not a defect.

The white gold that isn't white

White gold was developed in the 1920s as a substitute for platinum, and it comes in two families. Nickel-bleached white gold is gold with nickel, copper and zinc: harder, cheaper, and the mainstay of commercial production. Palladium-bleached white gold is gold with palladium, silver and a little copper or zinc — a plumb 14 or 18 karat palladium white typically runs something like 3 to 15 per cent silver, 1 to 3 per cent copper and zinc, and 10 to 21 per cent palladium. It is softer, it solders more cleanly, it is nickel-free, and it costs substantially more because palladium does.

Here is the part nobody tells you at the counter. Neither family is actually white. Both are pale yellowish-grey metals — palladium white a little cooler and more convincingly neutral, nickel white slightly warmer — and neither looks anything like the bright chrome-white you saw in the shop window. That brightness is rhodium, electroplated at the factory over essentially every white gold piece sold at retail, and it is the subject of the next chapter. So when your ring begins to look faintly warm and yellowish after a year, particularly on the underside of the shank where it rubs against your finger, nothing has gone wrong and nothing is fake. You are simply seeing the metal you actually bought.

This misunderstanding is so widespread that a regulator has ruled on it. In its 2018 revision of the Jewelry Guides, the United States Federal Trade Commission stated that it is deceptive to fail to disclose a surface application of rhodium on an article marked or described as precious metal — and the reasoning given was precisely that consumers mistake worn rhodium plating for tarnish. That is an unusual thing for a regulator to say out loud, and it tells you how common the confusion is. Australia has no equivalent rule, which is exactly why I put it in a handbook instead.

Nickel, skin, and a law Australia does not have

Nickel is the contact allergen that turns up most often at a jeweller's bench, and the Mayo Clinic prevalence figures cited in trade guidance put it at up to around 17 per cent of women and 3 per cent of men. On a nickel white gold ring, the rhodium plating acts as a barrier between the alloy and your skin, which produces a characteristic pattern I see often: no reaction at all for a year or two, then redness and itching that appears suddenly. Nothing changed in your body. The plating wore through.

The European Union has regulated this since the Nickel Directive of 1994, now carried into REACH: skin-contact items may release no more than 0.5 micrograms of nickel per square centimetre per week, and piercing posts no more than 0.2, tested to the EN 1811 method in artificial sweat. Australia has no equivalent nickel-release law. If you know you react to nickel, the practical answers are palladium white gold, which is nickel-free and looks acceptable even unplated, or platinum, which never needs plating at all. Ask the question before you order rather than after; if you are designing something with us, it is one of the first things we settle when we design a ring.

V Rhodium: The Maintenance Nobody Quotes You For

A layer of rhodium — a platinum-group metal rarer than gold — under two microns thick sits between you and the true colour of your white gold ring. Here is what keeping it costs, in Australian dollars, for the life of the piece.

Every white gold ring sold at retail is, in one specific sense, a subscription. The bright chrome-white finish you fell in love with is not the metal; it is a plated skin over the metal, and it wears off on a schedule. Nobody says so at the point of sale, which is not usually dishonesty so much as habit — the plating is so universal that the trade has stopped thinking of it as a separate thing. But it is a separate thing, it has a price, and that price recurs for as long as you own the ring.

What rhodium is, and what it is worth

Rhodium is one of the six platinum-group metals, and it is rarer than gold or platinum. It is also brilliantly, almost mirror-white, extremely hard, and chemically inert — an ideal surface and an impossible structural material, since it is far too brittle to make anything from. Its price history is spectacular in a way that tells you something about the supply. Rhodium traded around US$6,000 an ounce before 2021, then spiked to roughly US$29,800 an ounce in March 2021 after a converter-plant failure at a South African producer removed a large slice of world supply almost overnight, and had settled back to around US$4,400 to US$4,750 an ounce by late 2024. You are not, however, paying for much metal. A plated layer is measured in microns, and the cost of a replate is overwhelmingly labour, preparation and bench time rather than rhodium.

How thick, and how long

Professional rhodium plating is applied at roughly 0.75 to 2.0 microns, according to Brilliant Earth's published guidance. To put that in perspective, the bright finish on your ring is one or two thousandths of a millimetre thick, and it is being rubbed against your other fingers, your keys, your steering wheel and your desk every day.

How long it lasts is genuinely contested, and I would rather show you the disagreement than pretend it away. Brilliant Earth publishes six to twelve months for a daily-worn ring. Repair specialists — Quick Jewelry Repairs among them — quote twelve to twenty-four. Both are sourced, both are describing real experience, and the difference comes down to plating thickness, how hard the wearer is on their hands, and skin chemistry, which varies more between people than most buyers realise. The honest framing is six to twenty-four months for something worn every day, tending to the short end if you work with your hands, and years for a piece worn occasionally. A dress ring that lives in a box will hold its plating for a decade.

The wear pattern is diagnostic. Plating goes first on the underside of the shank and on the high points of any texture, because that is where the friction is. If the top of your ring is bright and the back is warm and dull, that is rhodium loss, not damage, not tarnish and not a fake.

What replating costs in Australia

Published Australian prices are easier to find than most people expect. Xennox Diamonds in Brisbane quotes from about A$60 to A$120 for a fine engagement ring. Gerard McCabe in Adelaide lists A$185 for white gold rings and A$225 for two-tone work, where the yellow sections must be masked before plating. The general Australian range quoted across the trade is A$100 to A$200. In the United States the comparable figures are US$50 to US$150, with simple bands at the lower end and work above US$120 where porous or heat-sensitive stones must be unset first.

That last clause is worth pausing on if you own coloured stones. Rhodium plating involves cleaning, electrocleaning and an electrolytic bath, and porous or treated stones — opal, turquoise, pearl, emerald, anything oiled or fracture-filled — should not go through it. They must be unset and reset, which is bench labour on top of the plating charge and a small risk to the stone each time. We will not put a set opal through a plating cycle, and any jeweller who offers to is not doing you a favour.

Now the arithmetic nobody does at the counter. Take the middle of the Australian range, A$150, and the middle of the frequency range, every eighteen months. Over forty years of daily wear that is roughly twenty-six replates and somewhere near A$4,000 in today's money — more than many people spend on the ring's metal in the first place. I am not telling you that number to frighten you off white gold, which is a perfectly good material. I am telling you because it belongs in the comparison you make on the day, and because it is never in the quote.

The two ways out

There are exactly two ways to stop paying it, and both are decisions made before you buy rather than after. The first is palladium white gold, which is nickel-free and pale enough to look entirely respectable unplated — slightly warmer and softer in tone than rhodium, more like a very fine grey-white than chrome. Many people prefer it once they have seen the two side by side, and it costs more up front because palladium does. The second is platinum, which is white the whole way through and never needs plating for as long as the ring exists. Chapter VIII does the platinum sums properly.

If you keep the rhodium, two habits extend it: take the ring off for washing up, swimming and hand cream, and never let a rhodium-plated or vermeil piece near an ultrasonic cleaner or an abrasive polishing wheel, both of which strip plating faster than years of wear. Warm water, a drop of mild dish soap and a soft brush is the correct cleaning method, and it is what the Gemological Institute of America recommends for very nearly everything.

VI The Honesty Ladder: Solid, Filled, Vermeil, Plated, Tone

Six rungs from solid karat gold down to gold tone, each with a legal definition in the United States and none at all in Australia — and the one blunt fact that every rung below solid gold has in common.

Almost every guide you will read presents these categories as a lifestyle matrix: gold filled is "great for everyday", vermeil is "perfect for special occasions", plated is "ideal for trend pieces". That framing is comfortable and it is wrong, because it hides the structure. These are not six equivalent styles. They are a hierarchy of how much gold you are actually buying and how long it will stay on the object, and the descending order is a descending order. Read them that way and the whole category becomes easy.

The definitions that follow come from the United States Federal Trade Commission's Jewelry Guides at 16 CFR Part 23. I use the American definitions throughout for a reason I will come to: Australia does not have any.

Rung one: solid karat gold

Gold all the way through, at a stated fineness. There is no coating to wear off, the piece can be sized, soldered, re-tipped and re-polished indefinitely, and it has scrap value at the refiner on the day you tire of it. In the United States the National Gold and Silver Stamping Act, as tightened in 1981, permits a marked article to assay no more than 3 parts per thousand below its stamp — 7 parts including solder — and requires the quality mark to be accompanied by the maker's or importer's registered trademark on the article itself. Note how much stricter CIBJO's international position is: no negative tolerance whatsoever. A serious maker works to the strict standard.

Rungs two and three: gold filled and rolled gold plate

Gold filled is genuinely the best of the coated categories and is routinely undersold. Under 16 CFR §23.3 it is a gold alloy of at least 10 karat mechanically bonded to a base — heat and pressure, not electroplating — where the gold layer is at least one-twentieth, five per cent, of the weight of the metal in the entire article. It is marked with the fraction and the fineness together: "1/20 12K G.F." Because the layer is bonded and thick by coating standards, well-made gold filled can survive many years of wear, and it is the sensible choice for costume pieces that get real use.

Rolled gold plate is the same mechanical bonding at a thinner fraction. The 2018 revision of the Guides advises a minimum of one-fortieth and requires the fraction to be disclosed, so you see marks like "1/40 14K R.G.P." As little as half the gold of gold filled at the advisory floor, and correspondingly shorter-lived.

Rungs four to six: vermeil, electroplate and gold tone

Vermeil, at 16 CFR §23.4, is a base of sterling silver coated on all significant surfaces with gold of at least 10 karat, at a minimum thickness equivalent to 2.5 microns of fine gold. That thickness is the point of the category: typical fashion plating carries under 0.5 micron, so vermeil's floor is around five times a standard plating and twenty to twenty-five times a flash coat. Good vermeil genuinely outlasts cheap plate, and on a sterling base rather than brass it has a little residual silver value.

Two caveats are almost never printed by the brands selling it. The first is that FTC Note 1 to that section expressly permits a maker to interpose a base-metal layer — nickel, typically — between the silver and the gold, provided it is disclosed. "Vermeil" therefore does not mean nickel-free, and the widespread claim that vermeil is hypoallergenic by definition is simply false; it depends entirely on construction. The second is that 2.5 microns is still a coating measured in microns. Sweat, perfume, chlorine and friction will take it through to the silver eventually, and once through, it cannot be repaired in the way solid gold can — it can only be replated.

Gold electroplate is an electrolytic coating of at least 10 karat gold at a minimum of 0.175 microns; heavy gold electroplate requires 2.5 microns, the same floor as vermeil but over any base metal rather than sterling. Coatings thinner than 0.175 microns cannot honestly be called electroplate at all, and the trade terms for them are "gold flashed" and "gold washed". At the bottom, gold tone, gold colour and gold finish are descriptions of appearance with no gold-content requirement whatsoever. They are not lies. They are simply not claims.

One update worth knowing, because a great many guides still have it wrong: since August 2018 the FTC has permitted articles below 10 karat to be described as gold in the United States provided the actual fineness is disclosed. The old "10K minimum to say gold" rule is gone.

The Australian blank, and the one blunt fact

Now the part that matters most for you, standing in a shop in Sydney or Perth. None of the above is Australian law. We have no statutory definition of vermeil, no statutory plating thresholds and no compulsory hallmarking. Australian retailers commonly recite the American standards, which is fair enough, and some assert an Australian "1 micron vermeil standard" — I could not locate any Australian law, regulation or industry code that establishes one, and the Jewellers Association of Australia's consumer guidance does not define plating terms at all. A seller quoting a local one-micron standard is, as far as I can tell, quoting themselves. What does apply is the Australian Consumer Law's prohibition on misleading or deceptive conduct, which covers consumer purchases from Australian sellers and gives you a genuine remedy when a description is false. Ask for the plating thickness in microns and the base metal, in writing, and a good seller will simply tell you.

And the blunt fact that no lifestyle matrix will print: every rung below solid karat gold is a consumable. Gold filled, rolled gold plate, vermeil and electroplate all have a service life measured in years and a scrap value at the refiner of approximately nothing. That does not make them dishonest products — a modestly priced vermeil chain honestly sold as vermeil is a good buy for a great many people, and I would rather someone wore a beautiful plated piece daily than kept solid gold in a drawer. It makes them consumables, and consumables should be priced, described and expected as such.

VII Hallmarks, Stamps and How to Actually Test Metal

Britain has compulsory assay, India has a six-character code you can check on your phone, and Australia has neither — so here is how to read a stamp, and how to test the metal underneath it.

A hallmark and a stamp are not the same thing, and the difference is the whole chapter. A hallmark is applied by an independent assay office after the metal has been tested. A stamp is applied by whoever made the piece, on their own authority, describing what they say it is. Britain has hallmarks. Australia has stamps. Both look like small numbers punched into the inside of a ring, and telling them apart is one of the more useful skills a buyer can pick up in an afternoon.

Britain, and the system everything else is measured against

In the United Kingdom, hallmarking is compulsory before sale above quite low weight thresholds: gold above one gram, silver above 7.78 grams, platinum above half a gram and palladium above one gram. Four assay offices survive, each with its own town mark — the leopard's head for London, the anchor for Birmingham, the rose for Sheffield and the castle for Edinburgh — and a full British hallmark carries the sponsor's mark, the fineness in millesimal figures and the assay office mark, often with a date letter. The fineness marks you will see are 375, 585, 750, 916 and 999 for gold, 925 or 958 for silver, and 950 for platinum.

One corollary catches people out constantly. Because the thresholds are weight-based, a tiny solid gold stud earring can be entirely genuine and perfectly legal without any hallmark at all, simply because it weighs under a gram. The absence of a mark on a very small piece is not evidence of fakery, and I have seen people talk themselves out of good jewellery on exactly that misunderstanding.

India, America, and the Australian blank

India runs the other rigorous system, and it has been tightened recently. Bureau of Indian Standards hallmarking became mandatory under a Quality Control Order of 23 June 2021, phased in district by district, and since 1 April 2023 every hallmarked piece must carry a six-character HUID code — a unique identity that can be checked in the BIS CARE app on a phone while you are standing in the shop. Indian hallmarked grades run 14K, 18K, 20K, 22K, 23K and 24K, with 916 the standard mark on the 22 karat jewellery that dominates the market. If you are buying gold in India, or buying Indian gold here, that six-character code is a real verification tool and you should use it.

The United States has no hallmarking system whatsoever. Quality stamps are self-applied under the Stamping Act's trademark and tolerance rules and enforced only through Federal Trade Commission or private action after the fact. Australia is in the same position, with one wrinkle: we have neither government assay offices nor compulsory hallmarking, and the closest thing to a national mark is the voluntary members' marking standard operated by the Gold and Silversmiths Guild of Australia, which binds Guild members and nobody else. What we do have is the Australian Consumer Law, and the ACCC's own 2005 jewellery publication — which documented goods described as gold that were plated with under one per cent gold content — is the regulator's own illustration of why descriptions get tested rather than trusted.

Reading the stamp in front of you

The common marks are worth memorising. For gold: 375 is 9K, 585 is 14K, 750 is 18K, 916 is 22K and 999 is 24K, and you will also see the karat written directly as 18K or 18KT. For silver, 925 is sterling and 999 is fine silver. For platinum, 950, PLAT or PT950. Below solid, the letters tell the story: GF is gold filled, usually with a fraction in front as in "1/20 12K G.F."; RGP is rolled gold plate; GEP is gold electroplate and HGE heavy gold electroplate; and a V or the word vermeil carries the American definition rather than an Australian one. If you meet a term this book has not covered, our gem lexicon keeps the definitions in one place.

Testing the metal, not the stamp

Because a stamp here is a claim rather than a verification, the useful question is how you test the metal itself. There are four methods and each has a specific blind spot.

X-ray fluorescence — XRF — is what a serious dealer or refiner will use in front of you. It is non-destructive, takes seconds, and technical comparisons put it within about 0.1 to 0.5 per cent of fire assay. Its blind spot is depth: XRF reads only a few microns into the surface, so heavy plating or a gold-plated tungsten core can return a confident and completely wrong reading. Anyone who tells you XRF is conclusive is overselling the instrument.

Acid testing is the cheap traditional method: a scratch on a touchstone, a drop of graded acid, a judgement about how fast the streak dissolves. It is surface-only, subjective, and involves hazardous acids. Thick-plated and gold-filled items pass it routinely. It is a screening tool, not proof.

Specific gravity testing weighs the piece in air and in water and compares the result to the density gold should have. It has the great virtue of examining the whole body rather than the surface — but it is defeated by hollow construction, by porosity, by set gemstones with densities of their own, and above all by tungsten. Tungsten's density is 19.25 grams per cubic centimetre against gold's 19.32. That is far too close for a density check to expose a tungsten-cored fake, which is precisely why tungsten is the material of choice for faking large gold items.

Fire assay is the definitive answer, accurate to roughly one part in ten thousand, and it is destructive — the sample is consumed. Refiners and assay offices use it; nobody uses it on a finished ring. Which leaves the practical protocol: for anything of real value, ask for XRF plus a density check plus a proper visual inspection under magnification for plating wear at the edges and seams. Three methods with different blind spots will catch what any one of them misses. And if you are buying a significant piece from someone unwilling to have the metal tested at all, that reluctance is itself the test result.

VIII Platinum and Silver: The Other Two Metals

Platinum is cheaper than gold by the ounce and dearer by the ring, and sterling silver tarnishes for a reason you can do something about — the honest case for and against both.

Gold takes up most of the oxygen in any conversation about jewellery metal, but two others matter enough to deserve a chapter. One of them is the metal I would choose for a stone I could not bear to lose. The other is the metal most of us already own without thinking about it, and misunderstand most completely.

Platinum by the ounce and by the ring

Start with the fact that surprises nearly everyone. Platinum is not the more expensive metal by weight, and has not been since 2015. On 23 August 2026, platinum spot stood at US$1,892.40 an ounce against gold at US$4,616.80 — platinum was trading at well under half the price of gold. This is not because platinum is abundant; annual mine supply is around 190 tonnes against something over 3,000 tonnes for gold. It is because the collapse of diesel-catalyst demand removed platinum's largest industrial buyer while investment flows piled into gold.

And yet the platinum version of a ring still costs more than the 18 karat white gold version, for three reasons that have nothing to do with the spot price. Jewellery platinum is typically 950 fine — 95 per cent platinum with about 5 per cent ruthenium, iridium or cobalt — against 18 karat's 750, so you are buying a much purer article. Platinum is denser, at 21.45 grams per cubic centimetre against gold's 19.32, so an identical design simply uses more grams of metal. And platinum is harder to cast, machine and finish, which shows up as bench hours. Guides that tell you platinum costs more because it is rarer and pricier are wrong about the metal price and right about the finished price for the wrong reason.

What the premium actually buys

Permanence, essentially. Platinum is white all the way through, so there is no plating to maintain and no rhodium cycle for the life of the piece — set against the arithmetic in Chapter V, that alone closes much of the gap over a few decades. It does not tarnish. And it behaves differently under a scratch: where gold is abraded away and lost, platinum is displaced, pushed aside rather than removed. Over years this produces the soft satiny patina platinum is known for, which can be re-polished bright at any time and which most owners come to like. More importantly, it is why platinum prongs hold up longer than gold prongs, and why the trade quietly prefers platinum for securing valuable stones. If you are setting something irreplaceable — a fine unheated sapphire, a stone with a story — that is the argument that matters.

The case against is honest too: it is heavier on the hand, which some people dislike and others love; it is dearer to buy and to work on; and a bench jeweller who rarely handles it will charge accordingly. White gold is lighter, cheaper and perfectly sound provided you accept the maintenance. There is no wrong answer here, only a decision that should be made with both sets of numbers visible.

Sterling silver, and why it goes black

Sterling is 92.5 per cent silver and 7.5 per cent other metal, usually copper, which is what the 925 stamp means and how the American definition at 16 CFR §23.5 puts it. Pure silver is too soft to hold a shape; the copper is what makes it wearable. The copper is also what makes it darken faster, which is the trade-off at the heart of the metal.

Tarnish is not dirt and it is not corrosion of the silver in the way rust is corrosion of iron. It is silver sulfide, formed when silver meets sulfur compounds in the air. Chemistry World's coverage of the modelling work on this is genuinely interesting: sulfur at parts-per-billion concentrations is enough to darken silver, and S8 molecules dissociate on contact with the silver surface, which is why the sulfide layer grows unusually quickly. Copper contributes its own black sulfide alongside, which is exactly why fine .999 silver tarnishes more slowly than sterling does. Coastal air, gas heaters, wool, rubber bands and cooked eggs are all local sulfur sources, which is why a piece can go from bright to grey in a drawer over a single humid Sydney summer.

A great deal of commercial sterling is also rhodium-plated or e-coated at the factory to delay all this — and the same FTC disclosure position from 2018 applies, because buyers mistake worn plating on silver for tarnish just as they do on white gold. If your "tarnish" is appearing in patches with hard edges rather than as an even film, you are looking at plating loss, not sulfide.

Living with silver

The good news is that tarnish is a surface film and it polishes off; the metal underneath is unharmed. Silver spot was around US$65.94 an ounce on 20 August 2026, up roughly 74 per cent year on year, so a solid sterling piece of any size is no longer the trivial object it once was. Store pieces dry, in airtight bags with anti-tarnish strips, away from rubber and wool. Wear them — skin contact and regular gentle cleaning genuinely slow tarnish compared with a piece left in a box. And remember that every polish takes a whisper of silver with it, which matters not at all on solid sterling and a great deal on silver-plated pieces, where enthusiastic polishing eventually goes straight through the plate.

IX What Metal Is Worth, and How to Keep It

Melt value, retail price, resale reality and insurance replacement are four different numbers for the same ring — plus the chlorine warning, the ultrasonic rules and the checklist I would want you to take shopping.

Before anything else in this chapter: we are gem merchants and gemmologists, not financial advisers, and nothing here is financial or investment advice. What follows is arithmetic and market data with dates attached, so that you can see how the four numbers attached to your ring relate to each other. What you do with that is your business and, if it matters enough, your adviser's.

Four numbers, one ring

A ring has at least four values, and almost every unhappy conversation I have about money comes from someone quoted one of them who assumed it was another. Melt value is what the metal weighs in gold. Retail is what a shop charges for the finished object. Resale is what somebody will hand you for it tomorrow. Insurance replacement is what an equivalent would cost to have made new. They are not close to each other and are not meant to be — but the gap between them is where disappointment lives.

The melt calculation, done properly

Melt value is weight times fineness times spot, and you can do it on your phone. Gold spot was US$4,616.80 an ounce on 23 August 2026, up around 36.6 per cent year on year on Trading Economics data, and in Australian dollars sat near A$6,410 an ounce on 21 August 2026 — roughly A$206 a gram of fine gold. A five-gram 18 karat ring holds 3.75 grams of fine gold, about A$772 of metal; the same ring in 9 carat holds 1.875 grams, about A$386. Subtract any stones first — they weigh something and they are not gold.

That is the floor. Retail sits well above it: trade estimates commonly put finished jewellery at roughly 250 to 400 per cent over melt, with luxury maisons well beyond 1,000 per cent and craftsmanship alone adding something like 20 to 55 per cent. Be careful with them: they come from American gold-buyer and trade-education sources rather than audited studies, so the direction is right and the precision illusory. Design, casting, setting, finishing and the gemmologist's time are real costs, and a hand-set ring is not a lump of bullion with a stone pressed into it.

Resale is the number nobody volunteers. On the secondary market, jewellery is generally bought at melt, and the figure quoted across the gold-buying trade is something like 5 to 30 per cent of the original retail or appraisal figure. Again, trade estimates rather than audited data. The making is what you enjoy; the metal is what you can sell. Buy the ring because you want the ring.

Insurance replacement is the fourth number and the most misread. A valuation states what it would cost to replace the item — deliberately higher than resale, often higher than what you paid — and it is not a statement of what anyone will pay you. In Australia we refer that work to the National Council of Jewellery Valuers, founded in 1984, whose members alone may use the NCJV Registered Valuer™ designation and which requires an approved educational standard and continuing professional development of its valuer members. The reasoning has a whole volume to itself in The Insurance & Valuation Handbook.

Chlorine, and the failure that arrives weeks late

Now the care advice that saves the most stones: do not swim in a chlorinated pool wearing karat gold. Chlorine attacks the copper, silver, nickel and zinc in gold alloys and causes stress-corrosion cracking: the gold is untouched, but the base metals leach out along the grain boundaries and leave a network of microscopic cracks. The failure is delayed, which is what makes it treacherous. A prong does not break in the pool; it breaks three weeks later while you are pulling on a jumper, and nobody connects the two events.

The laboratory numbers give the scale. Trade summaries report 14 karat prongs compromised in roughly 120 hours of exposure to 5 per cent household bleach, and pool-strength chlorine at around 5 parts per million does its damage cumulatively across a season of daily swims. Higher-karat alloys resist better because there is less base metal to attack, and 9 carat is the most vulnerable of the common alloys. The same warning covers spas, hot tubs and bleach-based cleaners. Take the ring off, and decide in advance where it goes.

Ultrasonics, and the checklist

On cleaning, the Gemological Institute of America's guidance is plain: warm water, a little mild dish soap and a soft brush is safe for very nearly everything. Ultrasonic cleaners are not. They are fine for diamonds, sapphires and rubies in sound settings, but never for fracture-filled, oiled or coated stones, or for porous gems — opal, turquoise, pearl, emerald. Ultrasonic vibration can also shake a stone loose from a worn prong — the machine is least safe on the ring that most needs cleaning. Rhodium-plated and vermeil pieces should never go near one, or near an abrasive wheel.

The checklist I would want in your pocket. One: ask what karat and colour alloy, and for white gold, whether it is nickel or palladium based. Two: ask whether it is rhodium plated, and what a replate costs there. Three: below solid gold, ask for plating thickness in microns and the base metal, in writing. Four: on a significant piece, have the metal tested — XRF plus density — rather than reading the stamp. Five: ask what the piece weighs — weight times fineness is a sum you can check yourself. Six: ask who will service it, and what a re-tip and a resize cost. Seven: get an insurance valuation from an NCJV Registered Valuer if it warrants one. And eight, for the stone rather than the metal: ask for full treatment disclosure in writing — every gem we sell carries it, with a Digital Gemstone Passport and free lifetime re-authentication. If a seller will not, that is your answer.

Two habits close the book. Have prongs checked once a year, which costs almost nothing and prevents the loss that costs everything; and take the ring off for the pool, the gym and the washing up. Metal is the part of your jewellery that does the work. If you would like a second opinion on a piece you already own, talk to our gemmologist.