Hallmarks are used to determine the karat, ie the gold content of a jewel. This article presents the main titrations and karat in jewellery.
What is a karat ?
There are two definitions for the term carat:
Gemological, therefore for a diamond or other gemstone, it is an unit of weight equivalent to 0.2g. Thus, the more carats a gemstone has, the higher its size is and thus its value increases.
In jewelry, it is used to measure the metal purity in the jewellery. Thus, 99.99% pure gold is 24 karats of gold. The consequence is that the karat is 1 / 24th of the total mass of an alloy. Thus 18k gold means that there is 75 % gold (18/24 * 100 = 75%). A 14 karat gold jewellery contains 58.5% gold.
What is a hallmark ?
Among the hallmarks, we distinguish two types :
Hallmarks status or legal title, denoting the purity of a jewel. Some examples below :
French hallmarks enable also to define the titration of a jewel. Below the mains french hallmarks :
Pure gold 99,99%
Gold 22 karats 91,6 %
Gold 18 karats 75 %
Gold 14 karats 58,5 %
Gold 9 karats 37,5 %
Silver 92,5 %
Silver 80 %
Platinum 85 %
Platinum 95 %
Platinum 90 %
Platinum 85 %
Master Hallmarks, designating the manufacturer’s brand of jewelery, goldsmith or Master. It is often hit in a diamond. The square punches generally means that the jewelry is gold plated or silver.
One can find the marks « G », « GALV », « Murat », « GOLD-PLATED » which are often signs plated jewelery brand, or plating by electroplating. This is called galvanic gilding.