At present, the "gold rush" continues to heat up, and new "routines" of adulteration have reappeared. Recently, the ** Jewelry and Glasses Testing Center of Ningbo Quality Inspection Institute was entrusted by the public security department to inspect a suspected fraud case. The appearance of the sample was very similar to that of pure gold, but further examination revealed that it was gold doped with "rhenium".
It is reported that the element "rhenium" has a silvery-white metallic appearance or gray or black powder, a melting point of 3180, and a density of 2104g/cm3。It is hard, wear-resistant, and corrosion-resistant. Its density is similar to that of pure gold, and it is difficult to distinguish it with conventional hydrostatic weighing, but its hardness and melting point are higher than that of pure gold.
*From Ningbo Market Supervision Bureau.
If it's the first or third case, you can usually just use is 1932 g cm3). However, it should be taken into account that there may be elements such as "rhenium", a metal with a density similar to gold, and the density method cannot be 100% distinguishable.
If it is the second case, take the sample submitted for testing as an example. The surface gold layer is thicker. If there is no damage to the surface, the data obtained using a professional X-ray fluorescence spectrometer can reach a percentage of pure gold; However, by filing the surface of the sample, a white metal layer is exposed. Then, if the field of view area is detected, a "rhenium" line will appear in the X-ray fluorescence spectrometer, confirming that the sample contains "rhenium".
For the above three cases, it is recommended to send it to a professional appraisal agency for testing.
The staff also said that "real gold is not afraid of fire" and "pure gold is very soft" are all private inspection methods and are not recommended for consumers. First of all, the temperature of "fire refining" cannot be provided in daily life, and ordinary gas stoves cannot reach it; Secondly, "soft and hard" is not only related to the purity of **, but also related to the thickness, shape and process of **, and ordinary consumers cannot make accurate judgments.
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**Jewelry mixed counter sales routine is deep