3d hard gold can be identified by fire. The surface of real 3d hard gold will not change color after fire, and the surface of fake 3d hard gold will be blackened by fire. You can also listen to voice identification. Real 3d hard gold will make a poop sound after impact, while fake 3d hard gold will make a clang sound. It can also be identified by magnets. Real 3d hard gold will not be attracted by magnets, while fake 3d hard gold will be attracted by magnets.
In addition, lettering on gold can also be used to identify the authenticity of 3D hard gold. In a regular jewelry store, the inside of gold will be engraved with its own brand name and gold purity, usually marked with the words "Pure Gold 999" and its own brand trademark. So 3D hard gold with similar lettering is real gold.