Most gold and silver jewellery carries a small number: 750, 585 or 925. Together with the weight, that number tells you how much pure gold or silver is in your piece. 750 gold is the same as 18 carat gold: both contain 75 percent pure gold. On this page you can read what the numbers mean, which finenesses are legal in Belgium, how the troy ounce works and why 18K with GP next to it is not solid gold. Then you work out for yourself how many grams of pure gold you have.
750
means 75 percent pure gold, or 18 carat
31.1035 g
is the weight of 1 troy ounce, the unit for precious metals
333
is the threshold: only above it may an alloy be called "gold" in Belgium
What is a carat?
The carat tells you how much of your jewellery is pure gold. Imagine dividing the weight into 24 equal parts. The carat is the number of those parts that are gold. At 24 carat everything is gold, apart from a tiny remainder: in practice 99.9 percent or more. At 18 carat, 18 of the 24 parts are gold, and the other 6 parts are another metal.
Think of a measuring jug with 24 marks. At 18 carat the jug is filled with gold up to mark 18, and the last 6 marks are another metal. At 9 carat it is the other way round: 9 marks of gold, 15 marks of something else.
Why not simply make it all gold? Pure gold is soft. Mixing in other metals makes it stronger and better to wear.
Yellow gold is usually mixed with silver and copper, white gold with palladium, silver or nickel. More copper makes the gold redder: that is how rose gold is made.
The rule is simple: the carat divided by 24 gives the share of gold. 18 divided by 24 is 0.75, so 75 percent.
8, 9, 14, 18, 22 and 24 carat
- 8 carat (333): one third gold. The legal minimum in Denmark and Greece. The number 333 sits exactly on the Belgian threshold: the law only allows the name gold above 333 thousandths.
- 9 carat (375): 37.5 percent gold. Found on British, Irish and French jewellery.
- 14 carat (585): 58.5 percent gold according to the hallmark, 58.3 by calculation. The most popular fineness in the United States, and a legal fineness in Belgium, the Netherlands and France, among others.
- 18 carat (750): 75 percent gold. The second legal gold fineness in Belgium. In practice, most gold jewellery in Belgium is 18 carat.
- 22 carat (916): almost 92 percent gold. In India the fineness of most jewellery, and that of the Krugerrand and the Sovereign.
- 24 carat (999 or 999.9): pure gold, as in bars and investment coins.
Carat in gold is not carat in diamonds
With gemstones, the same word means something else. There, a carat is a weight: 1 carat is 200 milligrams. That has nothing to do with the carat of gold. You can read more about stones on the page about gemstones. You can estimate the weight of the stone in your ring with the calculator in the Gold Check.
What does 750, 585 or 375 on your gold mean?
On a piece of jewellery, the fineness is usually not given in carats but in thousandths. Belgian law defines the fineness as the weight of the pure metal compared with the weight of the whole alloy. So 750 means: out of every 1,000 parts by weight, 750 are pure gold.
Internationally recognised gold finenesses include 375, 585, 750, 916 and 999. 585 stands for 14 carat. By calculation, 14 carat is 583.3 thousandths. The number on the hallmark is rounded up.
Under Belgian law, every part of a piece must have at least the hallmarked fineness. The number therefore promises a lower limit, not an average.
From thousandths to carats and back
- From carats to thousandths: divide the carat by 24. 18 carat becomes 0.750, or 750.
- From thousandths to carats: multiply by 24 and divide by 1,000. 585 becomes 14 carat. 900, the fineness of many old gold coins, becomes 21.6 carat.
999 and 999.9
999 is fine gold: 99.9 percent. 999.9, with four nines, is 99.99 percent. That is the purity of many investment bars and of the Maple Leaf. Both count as 24 carat. One hundred percent pure gold does not exist in trade. You can read more about bars and coins on investment gold and scrap gold.
Gold conversion table: carats, thousandths and grams
The most important column is the fourth: how many grams of pure gold are in 10 grams of that fineness. That figure is correct every day, whatever the price does. The table uses the number on the hallmark.
| Carat | Hallmark | Percent gold | Grams of pure gold per 10 g | Where you come across it |
|---|---|---|---|---|
| 8 | 333 | 33.3 | 3.33 g | Legal minimum in Denmark and Greece |
| 9 | 375 | 37.5 | 3.75 g | British, Irish and French jewellery |
| 10 | 417 | 41.7 | 4.17 g | American jewellery |
| 14 | 585 | 58.5 | 5.85 g | Most popular in the United States, legal in Belgium, the Netherlands and France, among others |
| 18 | 750 | 75 | 7.50 g | In practice, most gold jewellery in Belgium |
| 20 | 833 | 83.3 | 8.33 g | Legal fineness in Belgium and the Netherlands |
| 21.6 | 900 | 90 | 9.00 g | Old gold coins, such as the 20 franc Napoleon |
| 22 | 916 or 917 | 91.6 or 91.7 | 9.16 or 9.17 g | Krugerrand, Sovereign, jewellery from India |
| 24 | 999 or 999.9 | 99.9 or 99.99 | 9.99 or 9.999 g | Bars and investment coins |
Which finenesses are legal in Belgium?
The Belgian hallmarking law has three finenesses for gold: 833, 750 and 585. For silver there are two, 925 and 835, and for platinum one, 950.
This is set out in the Belgian law of 11 August 1987 on the guarantee of precious metal articles (in Dutch and French): the finenesses in article 3, the name gold or silver in article 19.
Separately, the law sets out when something may be called "gold": only if the fineness is higher than 333 thousandths. For silver and platinum that threshold lies above 500.
So there are two different questions, with a different answer.
- May it be called gold? Yes, from more than 333 thousandths.
- What is the lowest fineness for official testing by the state? 585, or 14 carat.
In Belgium, official testing by the state is voluntary. A manufacturer, seller or buyer may have a piece tested if they wish.
The lozenge, the oval and the hexagon
The shape of the Belgian fineness mark tells you straight away which metal it is.
- Gold: the number in a lozenge (a diamond shape), sometimes preceded by "au", for example au 750.
- Silver: the number in an oval, sometimes preceded by "AG", for example AG 925.
- Platinum: the number in a hexagon, a rectangle with cut corners, sometimes preceded by "PT".
A second small mark belongs next to the fineness mark: the maker’s mark, a symbol of their own in a barrel-shaped frame. Anyone in Belgium who offers a piece of gold, silver or platinum jewellery for sale must have these two marks on it. How to read the hallmark on white gold is explained on the page about white gold.
Does 9 carat count as gold in Belgium?
Yes. 375 is not a Belgian legal fineness, but it may be called gold in Belgium. You mainly find it on foreign jewellery, for example from the United Kingdom, Ireland or France.
Have you read on a website from the Netherlands that 9 carat is not gold? That is correct for the Netherlands, where something may only be called gold from 585. In Belgium that threshold is lower.
It does contain less gold: 9 carat contains exactly half as much gold as 18 carat of the same weight.
No hallmark? That proves nothing
Antiques, works of art and pieces that a hallmark would damage do not need to carry a legal hallmark in Belgium. Coins are not covered either. An old piece of jewellery without a hallmark is therefore not suspicious. How to find the hallmark and recognise real gold is explained in the Gold Check.
925 silver and other silver finenesses
Silver works the same way: the number gives the fineness in thousandths. 925 means 92.5 percent pure silver. In Belgium, 925 and 835 are the legal silver finenesses, and only what contains more than 500 thousandths may be called "silver".
925 is also called sterling silver. 958 is Britannia, a British fineness.
| Hallmark | Percent silver | Grams of pure silver per 100 g | Where you come across it |
|---|---|---|---|
| 800 | 80 | 80 g | German silverware, French silver (second standard), older Belgian silver |
| 835 | 83.5 | 83.5 g | Belgian and Dutch silver |
| 900 | 90 | 90 g | Older Belgian silver, old silver coins |
| 925 | 92.5 | 92.5 g | Sterling silver |
| 950 | 95 | 95 g | Old French silver (first standard) |
| 999 | 99.9 | 99.9 g | Silver bars and investment coins |
You work out the pure silver the same way as with gold: weight times fineness. A kilo of cutlery hallmarked 800 contains 800 grams of pure silver.
If cutlery carries a number such as 90 or 100, that is not a fineness: the cutlery is silver plated. What that number does mean is explained on the page about silver cutlery. More about selling silver is on selling silver.
Weight: grams, kilos and troy ounces
If you sell gold or silver in Belgium, it is weighed in grams, on scales that meet the legal measuring rules. Still, in the price and on investment gold another unit often turns up: the troy ounce.
1 troy ounce weighs 31.1035 grams. An ordinary ounce weighs 28.35 grams. So the troy ounce is almost 10 percent heavier.
| Unit | In grams |
|---|---|
| 1 troy ounce | 31.1035 g |
| 1 ordinary ounce | 28.3495 g |
| 1 troy pound (12 troy ounces) | 373.24 g |
| 1 kilo | 1,000 g, or 32.15 troy ounces |
Why precious metals are weighed in troy ounces
Out of tradition. The troy ounce has long been the unit for gold and silver, and the precious metals market still uses it, even in countries that otherwise count in grams and kilos. In the United Kingdom, the troy ounce may in fact only be used in trade for gold, silver and other precious metals. The name probably comes from the fairs in the French town of Troyes, but that is not certain.
The gold price is quoted internationally in dollars per troy ounce. You can find the price per gram and per kilo on the gold price page. You never need to calculate in troy ounces yourself: when you sell in Belgium, the weight in grams is what counts.
What "1 oz" on a coin means
An investment coin marked "1 oz" contains 1 troy ounce of pure gold, not 1 troy ounce in total. The Maple Leaf weighs 31.10 grams, because it is almost pure gold. The Krugerrand weighs 33.93 grams, because it contains copper, but it too contains 31.10 grams of pure gold. The Chinese Panda switched from 1 troy ounce to 30 grams in 2016.
Gold-plated, plaqué, doublé and gold filled: not solid gold
Doublé, plaqué, gold-plated and gold filled are all a layer of gold on another metal. How thick that layer is varies. What these words mean depends on the country and on who uses them.
Belgian law does not use the words gold-plated, plaqué or doublé. It speaks of pieces "covered" with gold. Such a piece may not carry a mark that looks like a fineness mark. A piece with a core of base metal may not be called "gold" in Belgium either. The Belgian hallmarking law sets no minimum thickness for gold plating.
If 18K or 750 is accompanied by GP, GF, RGP, HGE, "plated" or "doublé", the number only tells you which gold is in the layer. The piece itself is not solid gold.
Markings you come across
On foreign pieces you often see abbreviations such as GP or GF. Under the American rules they mean the following.
- GP (gold plate): a layer of gold on another metal, applied electrolytically or mechanically. The American rules require a layer that lasts reasonably long. As a guideline, an electrolytic layer should be at least 0.175 micron, a mechanically bonded layer at least 1/40 of the weight.
- GEP (gold electroplate): an electrolytically applied layer of at least 0.175 micron.
- HGE (heavy gold electroplate): the same, but at least 2.5 microns.
- GF (gold filled): a layer of gold alloy bonded to the metal, at least 1/20 of the total weight. The carat should be stated with it, as in 1/20 12K GF.
- RGP (rolled gold plate): like gold filled, but at least 1/40 of the weight.
- Vermeil: sterling silver with a gold layer of at least 2.5 microns.
- Plated, doublé, plaqué, gilt: also a layer of gold on another metal, not solid gold.
- Gold-coloured: only says something about the colour. There need not be any gold in it.
A worked example shows how little gold that is. A 20 gram bracelet marked "1/20 12K GF" has a layer of at least about 1 gram of 12 carat. That contains at least about half a gram of pure gold. With "18K GP" it depends on how the layer was applied. If it was applied electrolytically, it is a fraction of a micron to a few microns.
Recognising gold plating
A gold layer wears first at the edges, and then another metal shows through. How to check that and other signs is explained in the Gold Check.
Work it out yourself: from weight to grams of pure gold
With two numbers you know how much pure gold is in your piece: the weight in grams and the fineness.
- Weigh the gold. Stones, pearls and parts that are not gold do not count.
- Read the fineness. Turn the number into a decimal: 750 becomes 0.750, 585 becomes 0.585. If you only know the carat, divide it by 24.
- Multiply. Weight times fineness gives the number of grams of pure gold.
| Piece | Calculation | Pure gold or silver |
|---|---|---|
| Ring of 5 g, 18 carat (750) | 5 × 0.750 | 3.75 g gold |
| Chain of 10 g, 14 carat (585) | 10 × 0.585 | 5.85 g gold |
| Chain of 10 g, 9 carat (375) | 10 × 0.375 | 3.75 g gold |
| 20 franc Napoleon (900) | 6.45 × 0.900 | 5.81 g gold |
| Krugerrand (916.7) | 33.93 × 0.9167 | 31.10 g gold, exactly 1 troy ounce |
| Silver bracelet of 20 g (925) | 20 × 0.925 | 18.5 g silver |
A 10 gram chain in 9 carat contains as much gold as a 5 gram ring in 18 carat: 3.75 grams. So always look at the weight and the fineness together.
If you want to know what those grams are worth today, see the current gold and silver price per gram.
Unsure about the number in your jewellery?
A hallmark is an indication, not proof, and many old pieces do not have one. During a no obligation valuation we test and weigh your gold or silver in front of you, and show you step by step how much pure metal it contains. We come to your home in Flanders, or you come to a visiting day in your municipality.