How is the purity of gold measured?

What does it mean if a piece of gold is 18 carats or 24 carats? Traditionally, goldsmiths have used carat as the unit for determining the purity of gold, but in the investment world, thousandths have become the standard for indicating the quality of this noble metal.


Gold, which corresponds to the chemical symbol “Au,” is the most ductile and malleable of the noble metals. So much so that, by stretching a single gram, we can make a wire up to 2 km long.

The fact that it belongs to the noble metal family gives it some very special characteristics, as Nuria Rambla, executive assistant at 11Onze, explains, since these metals “do not oxidise in air or water, are unalterable over time, do not combine easily with other substances and resist acids well.”

What we know as raw gold is found in nature in the form of grains or nuggets mixed with other materials. It is then “put through a chemical and high-temperature process” to obtain what we call “pure gold.”

Carats or thousandths?

The purity of gold can be established in carats or in thousandths. The first measure is the one that has traditionally been used in jewellery, while in the world of investment the thousandths has become the norm.

If we measure it in carats, pure gold has 24 carats. This means that, out of 24 parts, 24 are gold. However, 18-carat gold has 18 parts gold and 6 parts other metal. As pure gold is very soft, it is common for jewellers to lower the purity by making alloys with other metals to make their goldsmiths’ pieces harder and more consistent.

If we measure it in thousandths, pure gold has 1,000. In any case, as Nuria Rambla points out in the video, 999.9 is considered to be “pure gold.” In the investment world, this gold can be found in bars or bullion coins. The former can weigh “from 2 grams to 1 kg”. As for the coins, they are issued by mints, which must state “the weight and purity”.


If you want to discover the best option to protect your savings, enter Preciosos 11Onze. We will help you buy at the best price the safe-haven asset par excellence: physical gold.

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Equip Editorial Equip Editorial

    Molt interessant!

  2. Santiago VázquezSantiago Vázquez says:

    Ara sí m’ha quedat clar!!!!

    • Silvia Granado says:

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      2 years ago
  3. Jordi MorenoJordi Moreno says:

    Molt interessant 👍

  4. Felip Tortosa EspadaFelip Tortosa Espada says:

    Sóc nou a la placa, amb il·lusió de forma part d’aquest projecte i poder fer una comunitat important i forta.

    • Mònica Cornudella says:

      Benvingut, Felip! Aquí ens trobaràs sempre, informant i formant de tot i de tota l’actualitat. Ens veiem a La Plaça!😉

      2 years ago
  5. Pere Maria EstremPere Maria Estrem says:
    Pere Maria

    Molt bona explicació.

  6. Manuel Bullich BuenoManuel Bullich Bueno says:

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