Academy · Foundation

What the numbers on your gold mean

916 and 22k are the same statement written twice. Karat counts parts out of 24. Fineness counts parts out of 1,000. Twenty-two parts in twenty-four is 91.6% gold, which is 916 parts per thousand — one number, two conventions, and Indian hallmarks print both.

That is the whole of it. What takes the rest of this lesson is the consequences: why the world's regions each settled on a different number, why a heavier piece can contain less gold, and why the purity figure — the one thing everybody checks — tells you nothing at all about whether you are being charged well.

The ladder

Pure gold is 24 karat. Everything below it is gold mixed with other metals, and the karat number says how much of the mix is gold.

• 24k · 999 — as close to pure as commerce gets. Too soft for most jewellery; the domain of bars and coins.
• 23k · 958 — rare in jewellery, seen in some traditional and ceremonial work.
• 22k · 916 — India's standard for jewellery. 22 ÷ 24 is 91.67%, rounded down to 916 so a piece can never fail assay on a rounding error.
• 21k · 875 — the Gulf standard.
• 18k · 750 — Europe's standard, and the usual choice for fine and stone-set work anywhere.
• 14k · 585 — the American mass-market standard.
• 9k · 375 — the lowest still legally sold as gold in the UK and much of the Commonwealth. Not permitted as "gold jewellery" in every market.

To convert either way: fineness = karat ÷ 24, and karat = fineness × 24. Everything else about purity is arithmetic on that one line.

What the other 8.4% is doing

Pure gold is remarkably soft — you can mark it with a fingernail. A 24-karat ring would deform in a pocket and wear through in years. The alloy is not adulteration; it is what makes the piece survive being worn.

It also decides the colour, which is worth knowing because the colour tells you something about the alloy:

• Yellow gold — gold with silver and copper in roughly equal measure.
• Rose and pink gold — more copper. The redder it is, the more copper is in it, at the same karat.
• White gold — gold alloyed with palladium, nickel or silver, and then almost always rhodium-plated to get the bright white finish. That plating wears off over a few years and needs redoing. It is a maintenance cost nobody mentions at the point of sale.
• Green, grey and other colours — different alloying metals again.

Colour and karat are independent. An 18k rose ring and an 18k white ring contain exactly the same amount of gold. If a shop suggests one colour is "purer" than another at the same karat, that is not a thing.

Why a heavier piece can hold less gold

This is the point where the arithmetic starts earning its keep. Two necklaces, side by side.

• A 10.0 g piece at 22k: 10.0 × 0.916 = 9.16 g of gold.
• A 12.0 g piece at 18k: 12.0 × 0.750 = 9.00 g of gold.

The second is 20% heavier and contains less gold. If the shop quotes both "per gram" without you converting, the comparison is meaningless. Weight only means something once you have multiplied it by fineness — and that product, the fine-gold content, is the quantity you are actually buying.

Why the regions differ

Nobody legislated these standards into existence. They settled where they did for reasons that still hold.

India at 22k. Where jewellery doubles as savings, the metal content is the point. Higher karat means more of what you paid for is gold, and more comes back when you sell. It also gives the deep yellow colour Indian buyers expect. The cost is softness — 22k marks and bends more readily than 18k, which is why heavy 22k work tends to be simpler in form.

The Gulf at 21k. A near-identical logic, one notch harder. 21k keeps most of the metal value while standing up better to daily wear, and it is what the souks are built around.

Europe and the US at 18k and 14k. Where jewellery is bought as adornment rather than as savings, durability and design freedom win. 18k holds a stone setting under stress in a way 22k does not, takes fine detail, and survives decades of wear. 14k goes further still, at the cost of holding a little over half its weight in gold.

None of these is right or wrong. They are answers to different questions — how much metal do I own, versus how well will this survive being worn — and the answer that suits you depends on which question you are actually asking.

Silver, platinum, and the same idea again

The fineness convention runs across the precious metals; only gold uses karats as well.

• Silver. 999 fine, 925 sterling — the near-universal jewellery standard — and 900 coin silver. India also recognises 990, 970, 900, 835 and 800 grades. Sterling is 92.5% silver with the balance usually copper, and the copper is why silver tarnishes.
• Platinum. Usually 950 — 95% platinum. Denser and considerably heavier than gold for the same piece, which surprises people who lift one.
• Palladium. Usually 950 as well, and much lighter than platinum for the same volume.

What purity does not tell you

Everything in this lesson describes the metal. None of it describes the transaction.

• It does not say what the piece weighs, or how much of that weight is stones rather than gold.
• It does not say what you were charged to have the metal made into this shape.
• It does not say whether the rate you were quoted was the day's rate.
• It does not say the piece is what it is marked as — that is a testing question, not a marking one.

A 22k stamp on a piece that is genuinely 22k is entirely compatible with an expensive purchase. Purity is the first question and the easiest one. The next four lessons are the ones that move money.

What this lesson cannot tell you

It cannot tell you which karat to buy. That depends on whether the piece is being worn or held, how it will be worn, and whether you expect to sell it back — and reasonable people land in different places on all three.

It also cannot confirm the mark is true. A number stamped on metal is a claim; verifying it is Lesson 02 and Lesson 03.

Kept in this browser only — no account, and nothing is sent anywhere. Finish all eight and you can claim a certificate.

Educational content only. Not financial, investment or tax advice. Aurix does not buy, sell, store or broker metal, and does not quote executable prices.