What does hg mean stamp on gold diamond necklace?

The "HG" stamp on a gold diamond necklace usually refers to the manufacturer's or designer’s hallmark, not the gold purity or diamond quality. It's often an abbreviation or initials of the jewelry maker or brand, used for identification and authenticity.

It’s different from purity marks like 14K, 18K, or 750, which indicate the gold content. If you see "HG" along with those purity marks, the necklace is likely genuine, and "HG" just tells you who made it.

For an exact origin, a local jeweler or appraisal service can help identify the specific maker behind the "HG" mark.