The stamp "18K HGE" on a piece of jewelry means that it is 18 karat gold with heavy gold electroplate. The "HGE" portion of the stamp means that it is heavy gold electroplate. Brass is another commonly used substance in jewelry.
All jewelry made from precious metals must be marked with a three-digit number, and sometimes other markings are also required. According to Foremost Jewelry, manufacturers often add the markings to the packaging or the tags instead of placing microstamps on small pieces. Gold plate jewelry also must be marked or stamped to certify the value of the metal. Some other markings that are used for gold electroplate jewelry are "GE," "EP," "GEP," "HE" and "HGE."