How to differentiate karats from gold ?

We often hear about carat for diamonds, but is it the same carat as for gold ? Not quite. The carat of the diamond expresses the weight, equivalent to 0.20 grams per carat. For gold, the carat designates a unit of measurement of purity. The higher the carat, the higher the purity of the gold used in the jewelry.

Gold is a noble and ductile material, but its sensitivity to scratches and shocks makes the use of pure gold restrictive. Pure gold jewelry must therefore be massive to best absorb trauma. To remedy this problem, jewelers create mixtures of metals, called “alloys”. Copper and silver are used for this. These alloys offer gold better mechanical resistance and allow the creation of finer objects.

The carat designation allows you to know the purity of gold contained in a piece of jewelry, a watch or any other gold object. The carat is divided into 24 parts, just like boats used to be:

• 18 carat gold: or 725 thousandths gold, or 75% pure gold, is one of the most used alloys. The remaining 25% is composed of copper or silver. It benefits from high gold purity. Conventional jewelry primarily uses 18-carat gold. On request, you can have objects made in 22 carat gold (91.7% gold);
• 14 carat gold: 58.5% pure gold and 41.5% zinc, silver or copper. It is mainly found in the Nordic countries and the United States;
• 9 carat gold: 375 thousandths gold, it is economical because it includes half as much pure gold as 18 carat gold. Harder, because of its alloy, it becomes more brittle. As gold is less present, the jewel is sensitive to oxidation.

24 carat gold, commonly called “pure gold”, is difficult to work. Very malleable, it is not very resistant to scratches, shocks and handling. The first production of a pure gold coin was made by the Royal Canadian Mint in 1979. However, this pure gold is not actually pure. The purity contained in a 24 karat gold gold bar or coin is 99.99%.

Recognize the purity of gold using hallmarks

24 carat gold is mainly used for making investment gold coins and bars. The value of a piece of jewelry, an object or a piece, is conditioned on its degree of gold used for its creation. This is why it is essential to know its purity during estimations. Jewelers and professionals in purchasing gold have specific techniques and means to know precisely the composition of the metals presented to them.

The hallmark is an obligatory mark in France, which allows an engraving on the metal to be identified using a magnifying glass. Depending on the purity of the gold, the indications are different:

• A seahorse: 24 carat gold;
• An eagle’s head: 18-carat gold;
• A scallop shell: 14 carat gold;
• A clover: 9 carat gold;
• Square hallmark: gold plated.

International hallmarks are different. The affixed mark inscribes the purity of the product directly in the gold (750 or 18 K for example).

Finally, pure gold bars have different and obligatory inscriptions:

• The title;
• Gross weight;
• The name of the founder;
• The serial number.

Gold and chemistry

The hallmarks allow rapid and precise identification of the purity of the gold. However, it happens that the assayers' marks and maker's marks disappear over time. It is therefore impossible to determine the purity of gold with the naked eye. This is why experts and jewelers use a non-destructive chemical process to know the quantity of gold used in the object.

The touchstone, or the touchau test, is a way of knowing the purity of a jewel. Specialists rub the ring on the jasper fragment, then apply a chemical mixture. There are several mixtures that react depending on purity. For a more precise study of your object, the use of a spectrograph or X-ray fluorescence is necessary.

Caratage is an essential step in the life of a piece of jewelry. You will need it in several situations, including during a repair or modification. In fact, the welds must be carried out with a gold content lower than the gold content contained in the object.

On the other hand, knowing the carat of a piece of jewelry allows you to estimate its value. Indeed, if you want to sell your jewelry or your necklace, you must know several elements:

• Purity;
• Weight;
• The price of gold.

These indicators together determine the selling price. Currently, the price of gold is around 1,838 euros per troy ounce. An 18-carat gold piece of jewelry weighing 10 grams does not have the same value as a 9-carat gold piece of identical weight. Conversely, 15 grams of 14-karat gold does not have the same financial value as 15 grams of 24-karat gold.

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