1. BOC Gold Bank was established in 1992. Is only managed by the head office of the People's Bank of China gold jewelry company, is the first gold wholesaler in China.
2. First of all, the gold of BOC Gold Bank is definitely pure and better than ordinary gold. This company is also the founding shareholder of Beijing Caibai, and its strength can be imagined.
3. BOC Gold Bank's gold popularity is not so high, because state-owned enterprises have never publicized it. Everyone who makes jewelry knows that.
Identification method of real and fake gold.
First: look at the color.
According to the different luster of gold, gold can be roughly divided into pure gold, k gold, real gold and fake gold. Red and yellow is the best color for gold, and the fineness is above 95%.
The fineness of true yellow is about 80%; The blue-yellow color accounts for about 70%; The fineness of yellow with gray is about 50%, so there is a formula of "seven green, eight yellow, nine five red, yellow and white with gray and half gold".
When we buy gold ornaments, if we see that the color of gold is blue, it means that the purity of gold is low; If the color of gold jewelry is yellow and red and yellow, it means that the purity of gold is very high.
For jewelry that has been hidden for a long time, there is a saying that "copper turns green, silver turns black, and gold never changes color".
Second: look at the logo.
The logo mentioned here is the English and numbers engraved on gold jewelry, and sometimes the words "pure gold 999" or "Au999" are engraved.
Usually, some gold jewelry brands will be accompanied by the precious metal appraisal certificate issued by the National Jewelry Quality Appraisal Center, which will also clearly indicate the detection number and gold content of the gold jewelry.
What we usually call pure gold means that the gold content of this gold jewelry is not less than 990%, which is expressed by "pure gold" or "Au990";
Thousands of pure gold means that the gold content is not less than 999%, which is expressed by "thousands of pure gold" or "Au999";
If it is all gold, it will be represented by the words "Au9999", and the content of all gold is higher than that of all gold.
Some gold ornaments will also be marked with 24k, that is, 18k. If it is 24k, it means that the purity of gold is above 99.6%, and it is pure gold or red gold. If it is 18k, the gold purity is 75%.
Third: look at the quantity.
Compared with other materials, the proportion of gold is relatively high.
Compared with copper of the same size, a small piece of gold feels heavier because of its higher density. After understanding this feature, you can use real gold jewelry to weigh and find the feeling.
Real gold jewelry will feel like falling off when worn on your hand; If it is fake, there will be a feeling of lightness.
Sometimes when we watch costume movies and TV series, we may see such a plot. Some people will tell the truth by biting gold with their teeth.
Because the hardness of pure gold is low, if you take a bite, real gold will leave teeth marks. This also shows from the side that the hardness of pure gold is not very high. If the hardness is too high, it may not be pure gold.
Fourth: Listen to the sound.
When high-quality gold jewelry is knocked or thrown to the hard ground, it will make a dull and low sound of "poof-poof-poof", which has no rhythm and elasticity.
K gold has rhyme, sound and elasticity. The greater the elasticity, the sharper the rhyme and the older the color.
Fake or low-quality gold sounds crisp and dull, generally making a "Dangdang" sound, with a lingering sound, and violently beating after landing.
Fifth: use acid points.
On the touchstone, grind the gold channel of the identified jewelry and the correct brand respectively, and test nitric acid on the gold channel with a glass rod. Because the chemical property of gold element is stable and does not react with acid, its color remains unchanged.
If it is not gold or impure gold, the path of gold disappears or changes.
Sixth: use fire.
Burn the jewelry to be identified (don't make it melt and deform), and observe the color change after cooling. If the surface is still golden, it is pure gold;
If the color darkens or turns black to varying degrees, it is not pure gold. Generally, the lower the fineness, the thicker the color, and all of them turn black, indicating that they are fake gold ornaments.
When it really burns red, it is quenched into water and its color remains unchanged. It really doesn't change color in case of fire, it doesn't resist fire, and it becomes dark purple.