Karat Guide: Gold Purity From 375 to 999 Explained

The karat system divides pure gold into 24 equal parts. When a piece of jewellery is made of 18 karat gold, it means 18 of the 24 parts are pure gold, while the remaining 6 parts consist of other metals such as silver, copper, zinc or palladium. These added metals are called alloying metals, and they are not added to "dilute" the gold but to make it harder, more durable and easier to work, since pure gold on its own is very soft.

The fineness system, which is the system used in Danish law, instead states the gold content as thousandths of the total weight. Here, 18 karat corresponds to 750 fineness gold, because 18 divided by 24 and multiplied by 1000 gives 750. Similarly, nominal 14 karat corresponds to 583.3 fineness, while the 585 stamp indicates 585 parts per thousand. It is this small rounding that often creates confusion when people try to calculate an exact figure and end up with a result that does not quite match the stamp.

In Danish jewellery shops you typically encounter four main categories of gold. 375 fineness, equivalent to 9 karat, is above Denmark’s 333 minimum fineness threshold and is used in cheaper rings and earrings where durability and price are prioritised. 585 fineness, equivalent to 14 karat, is the best-selling alloy in Denmark and many other countries, because it offers a good balance between gold colour, hardness and price. 750 fineness, equivalent to 18 karat, has a deeper, warmer gold colour and is often used for engagement rings, wedding bands and higher-quality jewellery, where appearance is prioritised over wear resistance.

Beyond these three, you also find 916 fineness, equivalent to 22 karat, which is popular in jewellery rooted in Middle Eastern and South Asian traditions, where high-gold-content jewellery holds strong cultural importance. 916 gold is markedly softer than 585 and 750 and is therefore less suited to jewellery exposed to daily wear, but is valued for its intense yellow colour and high metal value. Silver has its own fineness system, where 925 fineness (sterling silver) is the standard, while 875 fineness is seen in some older or foreign silver items, and 999 fineness denotes fine silver or fine gold in near-pure form, typically used for bars and coins rather than everyday jewellery, precisely because the pure metal is so soft that it bends and scratches easily.

Danish precious-metal legislation sets concrete minimum thresholds for how much pure metal an item must contain before it may be sold as gold, silver, platinum or palladium. According to the Danish Act on Precious Metals and Conflict Minerals, items of precious metal must in every individual part have a fineness of at least 333 fineness gold, at least 800 fineness silver, or at least 500 fineness platinum or palladium, unless the item can lawfully be marketed as precious metal in another EU/EEA country or in a country that has acceded to the 1972 international convention on precious metal control . In practice this means a gold item can never lawfully be sold as "gold" in Denmark if it actually contains less than 333 fineness, equivalent to roughly 8 karat.

The law also requires that items of precious metal sold under these designations be marked with both a fineness stamp and the manufacturer's name stamp . There is, however, an exception for very light items: gold, platinum and palladium items weighing less than 1 gram, and silver items under 1.5 grams, are exempt from the actual stamping requirement, but not from the requirement of a registered name stamp or from the requirement that the item genuinely meets the fineness it is sold under . This exception explains why you occasionally encounter very small, light pieces of jewellery with no visible stamp, even though they must still comply with the fineness requirements.

In Denmark, the Danish Safety Technology Authority (Sikkerhedsstyrelsen) holds the overall regulatory responsibility for precious-metal control in Denmark and Greenland, while the practical inspection task is carried out by Ædelmetalkontrollen (the Precious Metal Control) . The control is carried out by random sampling: Ædelmetalkontrollen makes unannounced visits to businesses that professionally manufacture or sell items of precious metal, takes samples from the stock, and has them analysed in a laboratory. If the samples show that an item does not meet the fineness stamp it carries, Ædelmetalkontrollen follows up to ensure the error is corrected, and the business can be fined .

It is important to understand that this control is sample-based and not a guarantee that literally every single item on the market has been tested at all times. The system relies heavily on the point of sale being responsible for the items genuinely containing the amount of precious metal they are stamped with, in every part of the product . For the consumer this means a stamp in itself is a strong indication of lawful trade, but not an absolute, individual guarantee for the specific piece of jewellery in your hand.

Because many pieces of jewellery are stamped with karat designations while Danish legislation speaks in fineness, it is useful to be able to convert between the two. The calculation is simple: karat divided by 24 and multiplied by 1000 gives the fineness. 9 karat corresponds to 375 fineness, 10 karat corresponds to 416.6 fineness, typically stamped 417. 14 karat corresponds to 583.3 fineness and is stamped 585. 18 karat corresponds exactly to 750 fineness. 22 karat corresponds to 916.6 fineness and is stamped 916, while 24 karat, i.e. completely pure gold, corresponds to 999 fineness or, more rarely, 1000.

It is worth noting that the small roundings between the theoretical fraction and the actual stamped figure are not signs of error or fraud, but a practical convention that the industry and legislation have adopted. When you see a piece stamped "585", you can therefore safely assume it corresponds to 14 karat, and when you see "750", it corresponds to 18 karat. Problems only arise if a piece is stamped with a figure that does not exist among the recognised alloys, or if the karat and fineness markings on the same item contradict each other - that can be a sign the stamping is not reliable.

An important distinction that many people overlook is the difference between the nominal karat designation used in everyday speech and the actual fineness that is legally binding once it is stamped on the item. When a seller advertises a piece as "18 karat gold", that is a nominal designation, but it is the actual fineness stamp - typically "750" - that legally obliges the seller to deliver an item with exactly that content throughout every part of the product. The fineness must also correspond to the stamp in every part of the item, meaning that a clasp or chain on a piece of jewellery must not have a lower fineness than the rest of the piece unless this is clearly disclosed .

This distinction matters in practice if you ever need to make a complaint about a piece of jewellery. It is not enough for a seller to refer to a verbal designation such as "14 karat" or "18 karat gold" - it is the stamped figure that is the legally decisive piece of information, and it is this figure Ædelmetalkontrollen compares against the laboratory analysis when taking samples . If you buy a piece of jewellery with no visible stamp, you should therefore always ask for documentation of the fineness rather than relying on a verbal karat statement alone.

One of the most widespread myths about testing gold is that you can determine authenticity by holding a magnet near the item: if it is not attracted, it is "real" gold. This test has a kernel of truth, since pure gold itself is non-magnetic, but it is far from reliable proof. Many counterfeiters are aware of this popular test and deliberately use non-magnetic metals such as brass, copper or stainless steel in their fakes, precisely because they know buyers look for a magnetic reaction. A piece of jewellery can therefore easily pass the magnet test while containing zero percent precious metal.

Conversely, there are legitimate gold alloys that contain a small proportion of nickel or iron as part of the alloy composition, which in rare cases can produce a weak magnetic reaction in a genuine, stamped piece. The magnet test can therefore give both false positives and false negatives and should never stand alone. Other popular home tests, such as biting the gold or dipping it in vinegar, are equally unreliable: at best they hint at something about the surface, but say nothing reliable about the overall composition throughout the piece. The only way to get a real answer is a professional analysis, like the one Ædelmetalkontrollen performs in a laboratory when sampling businesses , or comparable methods carried out by an independent appraisal expert, goldsmith or testing institute, typically based on acid testing, XRF spectrometry or touchstone testing.

The choice of fineness is rarely arbitrary. Lower finenesses such as 375 and 585 are popular because they combine an affordable price with good durability in everyday jewellery such as rings, bracelets and earrings that are exposed to constant wear. The alloying metals, typically copper, silver and zinc, markedly increase hardness compared with pure gold and make the jewellery more resistant to dents and scratches. At the same time, a lower proportion of precious metal naturally gives a lower material cost, which is reflected in the final sale price.

Higher finenesses such as 750, 916 and 999 are typically chosen when appearance, tradition or investment value are prioritised over wear resistance. 750 gold gives a richer, deeper colour often preferred for wedding and engagement rings, where the piece carries symbolic meaning rather than being subject to heavy daily use. 916 and 999 gold are often used in cultures where gold is traditionally regarded as a store of wealth and value rather than a purely fashionable accessory, and where the high purity and intense yellow hue are an important part of the item's value and meaning. The choice of fineness is therefore a deliberate compromise between price, durability, appearance and the cultural or symbolic use of the piece.

Always start by finding the stamped fineness figure, either as a plain fineness like "585" or a karat designation like "14K". At the same time, look for a name stamp showing who is legally responsible for the fineness stamp being correct - if both the fineness and name stamp are missing on an item that is not covered by the weight exemption for very light items, that is a clear warning sign. Also be aware that genuine silver of at least 925 fineness may in some cases be marked solely with the word "Sterling" instead of a numeric stamp , so the absence of a number does not automatically mean the item is not genuine silver.

If you are in doubt about a piece's true fineness and the value is significant, the best advice is to have it assessed by a professional goldsmith or testing institute able to carry out an actual material analysis, rather than relying on appearance, weight or a magnet test. Also remember that the law obliges the point of sale, not you as the consumer, to ensure the item lives up to the stamped content - so if suspicion arises after a purchase, it is relevant to contact the seller directly and, if necessary, Sikkerhedsstyrelsen or Ædelmetalkontrollen.