Abstract: Recently, "golden tridacna" is found abundantly on jewelry market in Beijing.The "golden tridacna" samples are primarily studied by using the conventional gemmological testing and UV-Vis spectrum testing.The results show that the "golden tridacna" sample is not the real tridacna, but the dyed oceanic conch, which has the diagnostic spiral layer.The dyed oceanic conch can be identified by the uneven colour distribution on the surface, the opaque yellow section and no fluorescence in the yellow section.It can also be identified by the UV-Vis spectrophotometer.