916
916 gold is nothing but 22-carat gold. 916 is basically used to denote the purity of gold in the final product, i.e. 91.6 grams of pure gold in 100-gram alloy. The figure 916 is basically 22/24 (22 carats by 24 carats). In a similar manner, 958 gold is 23 carats (23/24) and 750 gold is 18 carats (18/24).
916 gold is good for making intricate jewelry as pure gold is too soft. Delicate craftsmanship is not possible in 100% pure gold. As such, you should look for 916 purity gold when making purchases of jewelry as 22 karats are considered to be the best quality of gold purity for making jewelry and ornaments.
Hallmark
Hallmark gold, on the other hand refers to the certified quality of gold. The Bureau of Indian Standards or BIS awards hallmark on gold jewellery. Being hallmarked ensures that the quality of gold is as per claimed by the seller and customers aren’t duped when buying or reselling items. The BIS evaluates and indicates if a particular gold piece is up to mark on international purity standards. The gold is checked in one of the assaying centers of BIS spread over the country, currently over 330. Hallmarked gold is laser engraved so as to mark the gold with details such as:
- BIS logo
- Retailer’s logo
- Purity (916, 875 etc.)
- Year of certification
- Assaying center’s logo
In general, all gold pieces of jewellery and coins purchased from BIS certified retailers are hallmarked, though you should still check for the same. In case of purity certification, hallmarked gold is available in purities of 958 (23 carats), 916 (22 carats), 875 (21 carats) and 750 (18 carats). You should be more careful when buying gold from a neighborhood shop as they might not have been checked by the proper authorities.
KDM
KDM jewelry has a sort of history attached to it. However, using such an alloy gives more impurities to the gold. Let’s say you purchased a 22-carat gold jewelry piece that was worked on using this technique. So when this jewelry is melted when you sell it, you will get a lower purity of gold. You may have noticed that older jewelry is certified as 22/20 carat purity, wherein the jewelry at the time of buying was 22 carats purity and after melting it will have a purity of 20 carats.
This is where KDM jewelry comes in. KDM is an alloy of gold and cadmium with the divisions being 92% gold and 8% cadmium. This alloy also has a melting point lower than that of gold and maintains the purity of the base jewelry even when melted. However, KDM jewelry was found to have adverse health impacts on wearers and so the technology was banned and replaced by other advanced alloys.
