What does 916 mean? what does KDM mean? kdm marked jewelry and 916 marked jewelry. KDM hallmark

First of all, if you are looking for information on hallmarks, jewelry makers marks, or gold purity marks check out our educational pages under the brand tab you will find out much much more information there but we thought we'd summarize a few questions we get from time to time.
What does 916 & KDM mean?
916
This is quite simple, 916 represents the finesse of the gold in the jewelry.  91.6% of gold per 100%. The figure 916 denotes 22 carat (22 ÷ 24 = 916). And if you are wondering why not make jewels in pure gold, often times that depends on what the gold will be used for certain types of jewelry work better with 22k as 24k is much more soft and malleable.  There is some 99%  (24k) pure jewelry however delicate workmanship & intricate designs are not possible in pure gold.

KDM
 KDM & Non KDM jewelry
So what does KDM jewelry mean? Considers the basic process in jewelry crafting, Soldering. Solder, in order to make jewelry will have a melting temperature lower than that of gold, so just the solder melts and joins gold pieces without melting the gold parts. Earlier this solder was a combination of Gold and Copper. Though there was no particular ratio for this solder, generally it was about 60% gold + 40% copper. Since this alloy was strong and easy to make, it was widely used in jewelry. The downside to this solder is that, the purity of the solder is only 60%. So when this jewel is melted, the quality will be less than 22 carat. This is the reason your old jewels may carry an seal of 22/20 (20 carat represents the melting purity).
To overcome this problem and maintain a high standard of gold purity, cadmium began to be used in place of copper. The advantage being that unlike the traditional gold & copper solder, gold and cadmium can be mixed in a ratio of 92% + 8%. In other words the solder itself has a purity of 92%. This ensured the finesse of jewel remains constant regardless of the amount of solder used. Such jewelry using cadmium began to be widely known as KDM jewelry.
But shortly after the introduction of cadmium, it was banned as it was found to cause health issues for artisans working with it and wearing high amounts of cadmium.   After the ban, cadmium was replaced by advanced solders with Zinc and other metals. But the term “KDM” hung on and is still commonly used. So a KDM jewelry means it will have the same purity even when it is melted, as the solder itself has a purity of 92%.