The imprint "18k HGE" on gold essentially means that the gold is costume jewelry with little or no value. "HGE" stands for "hard gold electroplated," which means the object is not solid 18 karat gold throughout. "18k" refers to the type of plating used on the outer surface of the object.
Pure gold is 24 karats, or 24k. Therefore, 18 karat or 18k gold is 75 percent pure gold. However, if something has “HGE” stamped on it, it means that the object is made of a less valuable metal, such as copper, with a thin layer of gold on the surface to make it look like it’s made of solid gold. It’s only the thin layer on the surface of the object that has the 18-karat density. Electrochemical processes are used to bind the gold to other metals.
Gold plate is often used in costumes to save costs. It’s difficult to tell whether something is made of pure gold just by looking at it from a distance, so gold plating can be a good substitute. The gold plating also means that high percentages of gold, such as 18 karat, are used with gold plating at a cheaper cost when compared to a much lower karat that is solid gold.