The Choice of 18K Gold
18-carat gold (also written 18k, 18ct, or 18kt) is one of the most commonly used finenesses in the jewelry world because it is the most robust alloy for making quality jewelry: it allows for daily and durable wear as it is the most resistant against breakage, corrosion, scratches, and wear.
The History and Meaning of the Carat
The carat is a unit of measurement system invented in England in the 14th century. Its symbol is ct, or k/kt for some English jewelers. Its purpose is to facilitate trade by measuring the purity of gold: one carat represents 1/24th of the total mass of an alloy or 4.167%. In the case of carats, this means that out of 24 grams, there are 18/24 grams of pure gold, or 75%, and 6 grams of other metals that constitute the alloy of this fineness. It is also referred to as 750 thousandths, written 750‰.
But what are the other 6 grams made of?

Finenesses Vary by Country
Other "finenesses" exist and are used locally.
Only 24 and 18 are considered universal, while other alloys are considered specific to certain countries/regions of the world.

18-Carat Gold Compositions Differ According to Color
Since its discovery, yellow is no longer the only shade of gold. Today, there is also white, rose, etc. The compositions of these alloys vary according to the shades, here are some examples:
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18-carat yellow: 750‰ + 12.5% silver + 12.5% copper
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18-carat grey: 750‰ + 25% (silver; copper and palladium)
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18-carat white: 750‰ + 25% (silver; copper and palladium)
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18-carat rose: 750‰ + 5% silver + 20% copper
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18-carat blue: 750‰ + 25% iron or cobalt
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18-carat green: 750‰ + 25% silver
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18-carat red: 750‰ + 25% copper
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18-carat purple: 750‰ + 25% aluminum
The Hallmark
A hallmark is a tool used to mark jewelry and objects to certify the fineness of different metals.
If your jewelry doesn't have a hallmark, don't panic! Jewelry weighing less than 3 grams is not required to be hallmarked.
At Héloïse & Abélard, most jewelry weighs less than 3g, but we have chosen to engrave all our jewelry with a "750" mark to clearly indicate that it is always 18-carat gold.
The Choice of Recycled 18-Carat Gold
Recycled 18-carat gold also exists; at Héloïse & Abélard, all our jewelry is made from recycled 18-carat gold. If you want to know more, do not hesitate to consult our article on ethical gold.
