1 bite with your teeth, with bite marks?
"After real gold is bitten with teeth, it will leave a faint tooth mark, because gold is very plastic and a little soft. If it is not pure, it will be hard and will not bite. " In daily life and TV series, this method of testing the fineness of gold is more common.
It is understood that the Mohs hardness of human teeth is 6, the relative Mohs hardness of gold and silver is 2.53, pure copper is 3 and iron is 4. The hardness of many metal materials is relatively low, and biting with teeth will leave obvious bite marks. "Therefore, there is no scientific basis for using teeth to distinguish which is gold and which is not." National senior jewelry and jade experts said.
2. Look at the color, the yellower the purer?
The so-called "seven greens, eight yellows and nine five reds" is the experience of some gold collectors in the past to identify the purity of gold by color. Some people even think that the yellower the color of gold, the purer it is.
Experts say that golden yellow is an inherent physical property of gold, and it is not feasible to distinguish authenticity only by looking at the color with the naked eye without analysis and testing. Because gold can change color by adding other elements, there is no scientific basis for this identification method.
3. suck it with a magnet?
"If gold jewelry contains impurities, use a magnet to suck it. If it can be sucked up, it means that gold has impurities. " Recently, this gold identification method has been widely circulated on the Internet.
"Magnets can only adsorb three metals, iron, cobalt and nickel. Therefore, if other substances are added to gold jewelry, the detection method of magnets is impossible. " Wang Xuguang, stationmaster of the Gemstone Testing Station of the Municipal Quality Inspection Institute, said.
You can try these methods.
4. The density calculation method is simple and feasible.
So, is there a gold appraisal method that citizens can operate by themselves? Experts suggest that the density measurement method can be used for ordinary detection, which is relatively simple and easy to operate, and can exclude some adulterated gold.
It is understood that the density of gold is 19.26 g/cm3 to 19.37 g/cm3 at room temperature. Therefore, a certain amount of water can be injected into a high-precision measuring cup, and then the gold bars can be put into the water to measure the new amount of water. The volume of gold bars can be obtained by subtracting them, and then the density of gold bars can be obtained. If this density is between the standard values, then the gold bars are more likely to be of high color, otherwise they may be adulterated.
This method can eliminate most of the adulterated gold, but if other metals are added to the adulterated gold in strict proportion, it is impossible to distinguish, such as iridium and tungsten, whose specific gravity is similar to that of gold, and it is impossible to distinguish only by weighing the composition and measuring the density.
5. Do we have to find a professional organization to strictly test it?
It is reported that the most scientific way to identify gold is through destructive testing or spectral analysis in the laboratory, and both methods need professional institutions to operate. At present, the gemstone testing station of our quality inspection institute has carried out such testing business.
If private inspection is needed, the general inspection cost is about 100 yuan, which is different from destructive inspections such as fire in ordinary gold jewelry stores. The X-ray fluorescence spectrometer is used in Shibaoyu detection station, that is, the metal surface is irradiated by spectrum, and the metal composition is identified by the color reflected by spectrum. This method is not only extremely accurate, but also does not need to do destructive tests and does not damage the appearance of gold ornaments, which is more suitable for ordinary citizens.
At present, there are many kinds of instruments for detecting gold in the market, but each has its own shortcomings. If you want to see the authenticity of gold bars directly, you have to use ultrasonic method to directly detect the inside of gold bars. At present, the only instrument manufacturer on the market that can detect the inside of gold is Rongpu Technology Co., Ltd. ..