Gold and Silver Fineness – 999, 925 and 585 Explained
A ring says “585”, a chain says “925” and a coin says “999”. These numbers are the fineness: how much pure metal the alloy contains. Here we explain gold and silver fineness, how to convert it to carats, what the marks on coins mean and what tombac is – the alloy that often passes for gold.
What is gold and silver fineness?
Fineness tells you how many parts of pure metal there are in 1,000 parts of the alloy. 585 gold therefore contains 58.5% pure gold; the rest is other metals, usually copper, silver, zinc or palladium. These additions change the colour (yellow, rose or white gold) and harden the alloy – pure gold and silver are soft, so jewellery made from them would scratch and bend quickly.
Gold fineness chart
| Fineness | Gold content | Carats | Where you see it |
|---|---|---|---|
| 999.9 / 999 | 99.99% / 99.9% | 24 K | bullion bars and coins, e.g. Maple Leaf, Philharmonic |
| 916.7 | 91.67% | 22 K | Krugerrand, American Eagle, Britannia (until 2012) |
| 750 | 75% | 18 K | fine jewellery, watches |
| 585 | 58.5% | 14 K | the most common jewellery standard in Poland |
| 500 | 50% | 12 K | rare, older jewellery |
| 375 | 37.5% | 9 K | budget jewellery (common in the UK) |
| 333 | 33.3% | 8 K | the cheapest jewellery, mainly from Germany |
Which gold fineness is best? It depends on the purpose. For investment, purity matters – 999.9 or 916.7 – because you pay for grams of pure gold. For jewellery, 585 (14 K) is the usual choice: durable, scratch-resistant and cheaper than 750.
Carats and fineness – how to convert
A carat is another way of expressing the same thing. Pure gold is 24 carats, so 1 carat is 1/24 of the alloy. To convert carats to fineness, divide by 24 and multiply by 1,000: 14 K = 14 ÷ 24 × 1,000 ≈ 585. Note that gold carats are not the same as diamond carats, which measure weight (1 carat = 0.2 g).
Silver fineness chart
| Fineness | Silver content | Where you see it |
|---|---|---|
| 999.9 / 999 | 99.99% / 99.9% | collectible and bullion coins, silver bars |
| 958 | 95.8% | Britannia silver, older British coins |
| 925 | 92.5% | sterling silver: jewellery, cutlery |
| 900 | 90% | old circulation coins, e.g. US dollars before 1935 |
| 835 / 800 | 83.5% / 80% | cutlery, old European coins |
| 750 | 75% | pre-war Polish coins, e.g. 5 and 10 złoty from the 1930s |
What does 925 silver mean?
925 silver, or sterling silver, contains 92.5% silver and 7.5% other metals, usually copper. It is the jewellery standard, because pure silver is too soft for rings and chains. Sterling silver has real value, but it is not investment silver: buyers price it lower than 999 silver, and in jewellery you pay mainly for the craftsmanship, not the metal.
What fineness are collectible coins?
Modern silver collectible coins are almost always struck in 999 silver (Ag 999), increasingly in 999.9. Gold coins are usually 999.9 (Au 999.9) or 916.7. For a collector this means a 1 oz coin contains a full ounce of pure silver or gold – see how many grams that is in Troy Ounce – How Many Grams?
Where to find the fineness:
- on the coin itself – bullion coins carry it on the reverse, e.g. “1 OZ FINE SILVER 999”,
- in the issue specification – mints state the metal, fineness, weight, diameter and mintage,
- on the certificate, if the issue comes with one.
Don't look for an assay office hallmark on coins. Assay offices mark jewellery and precious-metal articles; the fineness of a coin is guaranteed by the mint that struck it.
What is tombac?
Tombac is a copper-zinc alloy, typically 80–95% copper and 5–20% zinc. Its warm, golden colour has made it popular for centuries for inexpensive jewellery, medals, badges and buttons. Tombac contains no gold and its metal value is minimal. The problem arises when a tombac item is sold as gold – on classified sites or at flea markets.
How to tell gold from tombac
- Check the marks. A gold item should carry a hallmark or a stamped fineness. No marks at all is the first warning sign.
- Compare the weight. Gold is more than twice as heavy as tombac (density about 19.3 g/cm³ against about 8.7 g/cm³), so a tombac piece feels light for its size.
- Look at worn spots. Tombac darkens over time, develops a greenish film and can turn skin green. Gold does not tarnish.
- A magnet won't help. Neither gold nor tombac is magnetic, so this test cannot tell them apart.
- When in doubt, ask a jeweller or an assay office. An acid test or an XRF analysis settles it in minutes.
Similar home tests for silver are described in How to Check if a Coin Is Silver – 5 Home Tests.
Frequently asked questions
What is the highest gold fineness?
In practice 999.99, but it is very rare. The standard for investment coins and bars is 999.9 – “four nines”.
How many carats is 585 gold?
14 carats. 750 gold is 18 carats and 999 gold is 24 carats.
Is 925 silver real silver?
Yes – it is real silver with 7.5% other metals. As a store of value, however, 999 silver coins and bars work better.
Is tombac worth anything?
Very little as metal. Only collectible items made of tombac, such as old badges or medals, can have value.
Summary
Fineness tells you how much pure metal is in an alloy: 999 is almost pure gold or silver, 585 is classic jewellery gold, and 925 is sterling silver. When buying coins, check the fineness in the issue specification, and watch out for tombac, which only looks like gold. Coins in pure metal are in our Silver coins and Gold coins categories. If you have a question about a particular issue, write to us – we are happy to help.