18 carat gold is one of the most commonly used alloys in high-quality jewellery. It is made up of 75% pure gold and 25% other metals. The higher the number of carats, the higher the pure gold content.

How do you calculate the price of a gram of 18 carat gold ?

The price of 18 carat gold varies according to supply and demand on world markets. 

The carat of gold is a unit of measurement used to assess the purity of the solid gold used in jewellery and valuable products. It represents the proportion of pure gold present in a specific alloy.

The carat system is therefore based on a scale of 24, where each carat is equivalent to 1/24th of the total mass of the alloy, the remainder being made up of alloying metals.

Let's take the example of an 18 carat gold ring weighing 10 grams. To calculate the amount of pure gold in the ring, you need to divide 18 by 24 (total number of carats) to obtain the proportion of pure gold in the alloy. In this case, the result is: (18/24 = 0.75). 

You can then multiply this proportion by the total weight of the ring in grams to find the amount of pure gold. In our example, this would be (0.75 x 10), or 7.5 grams of pure gold.

To find out the price of 18-carat gold, simply multiply the value found by the price in euros.

Comparison of gold prices according to carats 

The price of gold in France is subject to daily fluctuations, closely linked to variations in the world market. Here is an indicative list of the price of gold in France by carat, compared with the price per gram of 18 carat gold today :

• Price per gram of 9 carat gold : 17.40 €
• Price per gram of 14 carat gold : 27.40 €
• Price per gram of 18 carat gold : 37.99 €
• Price per gram of 22 carat gold : 47.21 €
• Price per gram of 24 carat gold : 53.77 €

How can you identify 18 carat gold without a hallmark ?

Even without a hallmark, there are various methods for identifying 18 carat gold: 

Using a magnet

Real gold has no magnetism and will not be attracted by a magnet. So if the object is magnetised, it is unlikely to be pure gold.

The density test

Gold has a higher density than other metals. By using a density meter, you can obtain a valuable indication of the composition of the object in question.

The acid test

By using specific acid solutions, you can assess the reaction of the gold and thus determine its purity. However, this method can cause slight alterations to the surface of the object.

So what is the best investment choice ? Should you buy gold, silver or platinum ? To help you make up your mind, we have provided a historical chart of the prices of these three precious metals. 

You can see how the yellow metal has evolved during global geopolitical crises, highlighting its invariable safe-haven value in times of tension. This visual representation offers a time perspective ranging from one day to twenty years, enabling an in-depth analysis of price trends.