Is it true that gold is black after it is burned?

First: it's real gold.

Second: black things are out of the way because of the time they are worn.

Third, it is necessary to observe whether the color of the gold has changed, if there is a change, or the color is not as bright as the previous color after burning, it proves that the purity is not high, at least it has not reached pure gold, or pure gold.

The purity, because you don't have **, can only be speculated.

Extended information: 1. Look at the color: **The higher the purity of the jewelry, the darker the color.

In the absence of a gold medal, the general fineness can be determined according to the following colors (based on lapis and gold. The so-called lapis gold is only contained**ingredients): dark red yellow color is more than 95%, light red yellow 90% 95%, light yellow is 80% 85%, blue yellow 65% 70%, color blue with white light is only 50% 60%, slightly yellow and white is less than 50%.

The commonly said seven green, eight yellow, and nine red can be used as a reference.

2. Weight: The specific gravity of ** is 1932, which is heavier than silver, copper, lead, zinc, aluminum and other metals. Like the volume of ** heavier than ** more than 40%, heavier than copper, heavier than aluminum.

**Jewelry should have a sense of sinking in the hand, and fake gold jewelry feels light. This method does not apply to ** jewelry inlaid with gemstones.

3. Look at the hardness: pure gold is soft, low hardness, shallow marks can be scratched with nails, teeth can leave tooth marks, ** jewelry with high fineness is softer than low fineness, the more copper content, the harder it is, and the bending method can also test the hardness, pure gold is soft and easy to bend, and the lower the purity, the less easy it is to bend. If it is made of raw gold, it is broken when bent, and the section has obvious sand grains.

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It can prove that we have a correct and rational view is a delicate question.

Gold will turn black.

Generally, jewelry will be oxidized and lose its luster when worn for a long time, ** jewelry blackening is often due to dust in the air and oil secreted by the human body and local blackening; In addition, ** jewelry and silver, copper chemical reaction, the formation of black silver oxide and copper oxide, this phenomenon does not belong to the quality of ** jewelry.

Gold fades, in many cases, due to chemical reactions caused by contact with external substances, which makes the surface of the surface metallic and dull or even fades. This is the case even with what we usually call thousand-foot gold jewelry.

Precautions.

If you have changed color and cannot clean it yourself, send it to a ** jewelry store and a professional will help you clean and maintain it. Avoid wearing jewelry, especially rings, when doing heavy work. When swimming, remove the ** jewelry to avoid chemical changes on the surface after touching seawater or pool water.

**Jewelry must be kept away from chemicals. After wearing, the ** jewelry often loses its luster due to stains and dust infection, at this time, as long as the ** jewelry is soaked in warm water with neutral detergent and cleaned, and then taken out to wipe dry.

Do not make pure gold jewelry touch perfume, hairspray and other highly volatile substances, otherwise it is easy to cause the ** jewelry to fade. **Rings and platinum rings are worn in the same hand, which is easy to cause the two to rub against each other, so that the appearance of the **ring is partially rubbed with platinum and white. Regarding the ** jewelry that turns white in this way, it can be planed with an agate knife, and it can also be rubbed vigorously with a coarse cloth (such as canvas) to restore the brightness.

Toothpaste, ammonia, acetic acid, soapy water, baking soda, etc. can wash gold. Toothpaste can remove dirt from the surface of ** jewelry. Because toothpaste contains abrasive particles, it is not possible to clean ** jewelry with toothpaste frequently, otherwise it will reduce the weight of gold jewelry and cause unnecessary losses.

Take a bottle and add purified water, drop a few drops of ammonia, put in ** jewelry, shake it vigorously a few times, take out the gold jewelry and wipe it dry with a soft cloth. <

Toothpaste, ammonia, acetic acid, soapy water, baking soda, etc. can wash gold.

1. Toothpaste can make teeth white, but also make **jewelry as bright as new, toothpaste can remove dirt on the surface of **jewelry. But this method is not very good, because the toothpaste contains abrasive particles, if you often use toothpaste to clean the ** jewelry will reduce the weight of the gold jewelry, causing unnecessary losses.

2. Ammonia has a very effective effect on the cleaning of the surface, and the method of helping ammonia cleaning is also very simple, first take a bottle and add pure water to it, then drop a few drops of ammonia into it, and finally put in the jewelry, shake it vigorously a few times and then take out the gold jewelry and wipe it dry with a soft cloth.

3. First take 1000 ml of warm boiled water, then add 200 ml of glacial acetic acid to make an aqueous solution, then put ** jewelry into the made aqueous solution and soak it for 10 minutes, then gently brush it with a soft brush dipped in hot water, and finally rinse it with water. It is best to use a cotton ball dipped in soapy water and anhydrous alcohol to scrub, so that the cleaned ** jewelry will become gorgeous.

4. Brush with soapy water mixed with a little alcohol, rinse and wipe dry with a soft cloth. Or use a flannel cloth dipped in toothpaste and gently sassafras until it is shiny. You can also go to the photographic equipment store to buy a pack of developing powder and pour it into 100 grams of water, stir it into a solution, including the used developer solution, immerse ** in the solution, take it out for about 5 minutes, and then rinse it with clean water, and then gently wipe it with a clean soft cloth, and the dirt can be eliminated.

5. If there is a black silver film on the surface of the jewelry, the more commonly used method is: 2 grams of salt, 7 grams of baking soda, 8 grams of bleaching powder, 60 ml of water, prepare a gold cleaning agent, put the gold jewelry in a bowl, pour the cleaning agent, two hours later, take out the gold jewelry, rinse it with water, and then wipe it with a soft cloth.

Blackening doesn't have to be fake.

Although there will be blackening of fake**, there are many reasons for blackening, such as blackening after contact with sweat, cosmetics, and oil.

**It has strong stability, and will not easily appear whitish, black and faded, etc., if there is a discoloration phenomenon, and this discoloration phenomenon can not be removed, it means that there is a problem with the ** itself, it may be fake, or it may be ** purity is not high enough.

Precautions for purchasing**

1. Weigh the weight. If the item is **, there is a heavy feeling, this is what people call the "golden pendant", and vice versa.

2. Look at the color. Pure gold shines brightly when exposed to intense light, which is not found in other metals, including copper.

3. Reviewing the rhyme. **Jewelry is thrown on the floor and makes a popping sound, the fake sound is high-pitched, and it is higher than **jumping.

4. Fold soft and hard. **It has the characteristics of good ductility and low hardness, pure gold is soft and soft, and copper strips are laborious.

5. Use acid spots. **Insoluble in acid, fake because of other active metals such as copper, it will react with acidic solutions.

**It will not be burned black, **it is difficult to oxidize with the air, and after burning, it can only become brighter, false**or too low purity**.

Put the gold bars. Or gold jewelry is burned on a fire for a while to observe its changes. As iridium binds with oxygen in the air, an oxidation reaction occurs.

Therefore, gold bars of insufficient purity will turn gray; Pure gold, on the other hand, will be red and shiny in color after being roasted by fire. However, this method may be destructive to jewelry.

Identifying adulteration

1. Whether there are white bright spots.

Cut the gold bars or gold jewelry with material scissors and use a magnifying glass.

If you see a white bright spot on its facet, it means that it is in the ** because ** and iridium cannot be fused together.

Doped with iridium. 2. Measure the specific gravity.

Measure the weight of a pure gold bar with a balance, then place the bar in a measuring cup and pour water over the bar. Then put the gold bar to be tested into the measuring cup, observe whether the scale of the water rises or falls, as long as it changes, it means that the gold bar is not pure gold. However, this method does not apply to gold jewelry, because there is air in it.

Really** it won't turn black when burned with fire.

**It will not be attacked and discolored by sulfur and oxygen at a simple high temperature, but it will be oxidized under certain conditions, or at a high temperature of 4000 degrees, pressurized, and with a catalyst, it will react very slowly with oxygen

It can be considered that it does not react, because under normal circumstances, there are few flames that can exceed 3500 degrees, and gold melts above 1000 degrees, so it is generally believed that real gold is not afraid of fire, that is, gold does not react with oxygen at high temperatures.

Why does it turn black when you come back and burn it with fire, and what is going on? Next, I will reveal the reasons for this phenomenon, I hope it can help you.

First of all, the operation steps of the fire test method are that it does not fade or dissolve at a high temperature of 1000, and at 1063, it begins to dissolve but does not change color. This method of burning with fire is also unreliable, and the general temperature cannot reach the level of identifying the authenticity of ** jewelry. We use fire to identify the jewelry to be identified red, after cooling to observe the color change, if the surface is still the original ** color is pure gold; If the color is darkened or darkened to varying degrees, it is not pure gold.

Generally, the lower the fineness, the stronger the color, and all turn black, which may indicate that it is fake gold jewelry, which is the first case. The second scenario suggests that this may also be a normal phenomenon, and the blackening may be the oxidation of the surface and the carbon deposits from your fire, and there will still be gold after wiping it with a dry cloth. Moreover, it does not oxidize at room temperature.

Blackening is a chemical reaction with mercury in your cosmetics or sulfur in the air. There is nothing directly related to purity. The fire cleaning method only burns off the dust and blackened elements on the surface, and the composition of the ** is not affected.

Because the ignition point of gold and silver is particularly high, under normal circumstances, even if it is burned by fire, it can maintain its original color, if your gold turns black after burning, it means that your gold is fake.

The blackening of the gold may be due to the low color that causes it to turn black after the fire, or it may be false**, or it may be because of the reaction with the sulfur in the air to cause blackening, and the surface oxidation and the carbon deposition of the fire form a chemical reaction that will also turn black, and it can be turned back to gold by drying it with a dry cloth.

If it were gold, would he turn black? There is such a saying: real gold is not afraid of fire to refine, no matter how he collects it, he will not become yan