My system is not decent

"Come on, young man, this is the spot gold I bought from the bank. Can you take a look? Some have black spots on them, and some have red spots. The bank said it's okay, but I don't believe it!"

The last aunt directly took out a large bag, which contained a lot of things in plastic.

After a short look, Chen Wenzhe found that this is really a big local tyrant.

There are gold bars, gold coins, and silver coins in it, and there are quite a few of them.

"You can show it to aunt at ease. I will pay the appraisal fee for so many things."

"No, one appraisal, no matter how many things there are, counts as one."

If it was calculated on a one-time basis, she might have to pay him [-] to [-] for these things.

Chen Wenzhe would not do such a black hearted thing.

"Young man is really good. There are more or less problems with these. You can take a look and watch them. I will help you get people to buy bracelets. I will definitely not let you suffer."

Chen Wenzhe was delighted when he heard it: "You bought these things from a regular bank, right? I mean, did you buy them at a bank, or did someone sell them to you?"

"I bought them at the bank. At the beginning, there were only a few problems, and I didn't pay much attention to them. Later, I found more and more problems, and the bank didn't give an explanation. You can identify them, so I can find trouble with them."

Looking at the aunt's expression, Chen Wenzhe knew that the bank should have given an explanation, but she no longer believed it.

If so, let her have a good look. !

The first thing I looked at was the gold bars. Sure enough, there were red spots on them, and I took out a plate of silver coins.

Many of them have black spots, and looking at the gold coins, there are red spots again.

Chen Wenzhe looked a little sweaty, there are problems with these, how many of them are okay?

"Can you remove the outer plastic wrap?"

"Okay, just take it apart!"

Chen Wenzhe opened a plate of gold coins and weighed them in his hand, it turned out to be pure gold.

A magnifying glass can be used to see that there are red spots on it, which are formed after iron oxidation.

But gold coins are pure gold, so where did the iron come from?

"Auntie, gold coins should be fine. They are pure gold. You can go to a gold store to measure it. It is not troublesome to check the density. As for the red spots, it is indeed the rust left after the iron has oxidized and rusted!"

"The gold coin is fine, but there is rust?"

"Yes, the gold coins are fine, at least this one is fine. If I'm not wrong, these should be fine. They are all genuine products. Things produced by national banks should be fine."

After reading a few more times, Chen Wenzhe generally understood what was going on. This problem was not an exception.

I often see news like this, saying that after someone bought an investment gold bar with a fineness of 999 in the bank, it rusted without opening the seal!

Obviously for the sake of insurance, I chose to buy physical gold in the bank. How could it rust?

And according to common sense, only iron will rust, right?

Is there a fake gold bar, and iron is hidden under the appearance of gold?

In this case, if you search the Internet casually, you will find a lot.

What's more serious is that in addition to investing in gold bars, even the pure gold commemorative coins, which are legal tenders, are also rusting.

The so-called rust, in life, mostly refers to iron objects, in a humid environment, after oxidation to produce ferric oxide.

The most direct effect of this chemical reaction is to make the original metal lose its good properties.

So rust has never left a good impression on everyone, especially the dull red color of ferric oxide, which is often used in the background of some horror movies, which makes people habitually feel bad.

One of the most important reasons why many people suspect that gold products are gold-plated iron is that the "rusty" color of gold is almost exactly the same as that of iron.

And once this kind of rust appears, people's first impression is that the gold is fake!

The gold in many people's hands is rusted, and the main phenomenon is "red spots".

The phenomenon of silver rusting is mainly "white spots", "white fog", "yellowing" and "blackening".

So, if it is really forged with iron, why are the colors of gold and silver rusted different?

Let’s first look at gold. As one of the most stable metals in its natural state, gold often gives people the impression that it can last forever.

Especially in some thousand-year-old tombs, lacquerware, silverware, bronze, and silk can hardly withstand the erosion of time. Only gold still maintains its original appearance when it is unearthed.

In contrast, the gold bars and coins we buy now are more mature in craftsmanship and have higher gold content. Why do you think that gold products are not as durable as unearthed cultural relics?

The gold and silver coins of the early countries were mainly used for export. If the gold coins really had "quality problems", it was likely to affect the country's credit.

For this reason, in 1989, the Gold Coin Corporation and the Mint jointly explored the cause of the "red spot".

After collecting and analyzing the erythema samples, it was found that its main components were silver and iron, that is to say, the red color on it was indeed rust caused by iron.

However, after testing the gold coins, they did not find that they contained silver and iron, so how did these silver and iron appear?

After simulating the coin making process, the testers finally locked the problem in the production environment and the coin pressing die.

Due to metal dust pollution in the production environment, the coin body will be stained with traces of silver and iron before packaging.

And these impurities, under specific temperature and humidity, will produce oxidation reaction, and finally lead to the appearance of erythema.

The testers deliberately adhered trace amounts of silver powder and iron powder to the gold coins for testing.

在35-50摄氏度、70-85%湿度的条件下，仅3天便出现了类似的红斑，且会越来越大。

In other words, as long as the impurity pollution on the finished coins is eliminated, the appearance of red spots can be prevented.

Of course, removing impurities requires more capital investment, and the prices of most common gold coins and investment gold bars are close to the price of gold, so considering the cost, the premium is not enough to support a more stringent process level, which has led to the fact that the erythema has not been able to Completely put an end to it.

For silver coins, there are more problems. First of all, the stability of metallic silver itself is not high, especially pure silver, which can react with various substances in the natural environment and is easily oxidized. This is also some silver jewelry. The reason why it doesn't take long to turn black.

After silver contacts sulfide, it will first turn yellow and then turn black, and the white spots are the silver chloride crystals produced after silver reacts with chlorine-containing substances.

If you encounter a humid environment, the speed of these reactions will only be faster.

In the case of a low production environment, many silver coins have been contaminated before leaving the factory.

Therefore, as long as it is not stored properly, even if the original factory is intact, it will still be oxidized and discolored in a specific environment.