Short answer. Karat is a fraction: parts of pure gold out of twenty-four. 24K is gold and nothing else. 18K is three quarters gold. 14K is a little under three fifths. Everything else in the piece is other metal, and that other metal is what makes the gold wearable. Higher karat means warmer colour and softer metal. It does not mean better, and on a plated piece it does not mean more gold — it describes the purity of the surface layer, not how much of it there is.
The fraction, in one table
| Karat | Gold content | Stamp | Colour | Hardness |
|---|---|---|---|---|
| 24K | 99.9% | 999 | Deep, almost orange yellow | Very soft; marks easily |
| 22K | 91.7% | 916 | Rich yellow | Soft |
| 18K | 75% | 750 | Warm, saturated yellow | Holds detail; still scratches |
| 14K | 58.3% | 585 | Lighter, cooler yellow | Harder; takes daily wear well |
| 9K | 37.5% | 375 | Pale, faintly grey-yellow | Hardest of these; more alloy than gold |
9K is worth knowing about in Australia specifically, because it is the karat a great deal of high-street gold here is made in, and 375 is the stamp to look for. It is legally gold. It is also more than 60% other metal, which is why it reads pale next to 18K and why it behaves differently over time.
Colour is the alloy, not the gold
Pure gold has exactly one colour. Every other shade in a jeweller's window comes from what is mixed with it.
Yellow gold is alloyed with silver and copper in roughly balanced proportions. More gold in the mix means a deeper, warmer yellow, which is why 18K reads richer than 14K side by side, and why 24K can look almost orange to an eye used to 9K.
Rose gold is the same idea with the copper turned up. The pink is copper, so a rose piece at the same karat contains the same amount of gold as the yellow one beside it.
White gold is gold alloyed with pale metals, and it is almost always finished with a rhodium plating to hold a bright, even white. That plating is a surface layer with a finite life, which is why white gold rings are periodically re-plated. It is a useful thing to know before comparing a white gold piece to a plated one on principle.
Hardness: why 24K is the wrong choice for a ring
Gold is soft. Pure gold can be marked with a fingernail under enough pressure, and a 24K band worn daily will go out of round, pick up dents from door handles and lose a crisp edge inside a year. The alloy metals are what give a piece the stiffness to hold a stone in a claw setting and keep an engraved line sharp.
That is the real trade, and it runs in one direction: the more gold in the metal, the less structure the metal has. 18K is the point most fine jewellery settles at because it is high enough to look unmistakably gold and hard enough to survive being worn. 14K goes further towards durability and gives up a little colour depth for it. For a solid piece meant to be worn every day for decades, neither of the extremes is the answer.
Where karat does not tell you what you want to know
Karat says nothing about weight, and weight is where the money is in solid gold. A hollow 18K chain can contain less gold than a heavy 14K one. Two solid rings at the same karat can differ by half their price on grams alone. If you are buying solid gold, the karat and the weight are two separate questions and you need both.
The plated twist, which is the part that matters
Here is where most karat guides stop being useful. On a plated or vermeil piece, the karat describes the gold in the surface layer. It does not describe how thick that layer is, and thickness is what decides how long the finish lasts.
So a 24K plated piece is not automatically longer-lived than an 18K one. It is a purer, warmer, deeper gold on the outside. Whether it stays there for one year or six depends on the thickness, on the base metal underneath, and on where you wear it. A pair of studs and a ring with the identical finish will age at completely different rates, because a ring lives against desks and steering wheels and a stud lives against nothing.
Two useful consequences. First, softness matters far less on a plated piece than in a solid one: the layer is supported by the core beneath it, so a 24K surface on solid sterling behaves nothing like a 24K solid band. Second, when someone quotes you a karat and nothing else, they have told you about colour and purity and said nothing at all about durability. That distinction — layer thickness against layer purity, and what each one is actually worth — is the whole subject of gold plated vs gold vermeil vs gold filled, and the fuller comparison sits in our Australian guide to gold-plated, vermeil and solid gold.
How the karats sit at Amaurine
We publish the maker's specification as given — karat and base metal — and every product page names its own. There is no single house karat, and any brand that quotes you one across a whole range is telling you about its marketing rather than its metal.
The highest karat we carry sits on a plated piece rather than a solid one. The Rivage Band Ring is zirconia on 925 sterling silver under 24K gold vermeil. The pieces that carry the word vermeil are specified as such by the maker, and each is gold over 925 sterling silver — the Nacre Baroque Pearl Bracelet in 18K, this ring in 24K. The body of the gold collection is 18K or 14K gold over solid 925 sterling silver — the Anneau Hoops are 925 sterling silver plated in 14K gold, a thin, plain circle at A$199 — and the cuffs, bangles and steel rings state their own karat too.
In solid gold there is no core and no finish: the metal is the piece, which is exactly why the karat is chosen for how it wears rather than for how it photographs. The material standards behind every Amaurine piece are on the Standards page.
Questions
What is the difference between 14K and 18K gold?
Proportion. 18K is 75% pure gold, 14K is 58.3%, and the rest of each is alloy metal. 18K reads as a warmer, deeper yellow; 14K is lighter in colour and harder, so it resists scratches and holds an edge better through daily wear. Neither is a grade of quality — they are two points on the same trade between colour and durability.
Is 24K gold better than 18K?
Purer, not better. 24K is 99.9% gold and has the deepest colour, but it is soft enough to mark, dent and go out of round, which makes it a poor choice for a solid ring or a claw setting. 18K is where most fine jewellery settles because it looks unmistakably gold and still survives being worn.
Does higher karat gold tarnish less?
Gold does not tarnish at any karat, so no karat is protecting you from that. What higher karat does reduce is the proportion of alloy metals — copper in particular — which are the parts that can react. In practice, on a well-made piece, this is a much smaller factor than how the piece is stored and what goes on your skin before you put it on.
What do the numbers 375, 585 and 750 mean?
They are the same information as the karat, written as parts per thousand: 375 is 9K, 585 is 14K, 750 is 18K, 916 is 22K and 999 is 24K. 375 is worth recognising in Australia, because a lot of high-street gold here is 9K — legally gold, and more than 60% other metal.
Does the karat tell you how long gold plating will last?
No. On a plated or vermeil piece the karat describes the purity and colour of the surface layer, not its thickness, and thickness is what decides how long it lasts. A 24K plated finish is a warmer, purer gold on the outside; whether it stays there for one year or six depends on thickness, the base metal beneath and where on the body the piece is worn.
Which karat should I buy?
For a solid piece worn daily, 14K or 18K: 14K if you want the hardest wear, 18K if you want the colour. For a plated piece, the karat sets the colour and the construction sets the lifespan — so read what the base metal is and how the layer is described, and treat the karat as an answer to a different question.
