What is the specific cause of the discoloration of gold?

After wearing ** jewelry for a period of time, many people think that this is the lack of color of ** jewelry, so the store negotiates or goes to the consumer association to complain, but it is told that the fading of ** jewelry is not the lack of color of ** jewelry, but other reasons, so, what are the reasons for this? **Discoloration or fading of jewelry is closely related to human sweat. 99% of human sweat is water, and the other 1% or so is waste and harmful substances in the human body, such as:

Chlorinated substances, lactic acid, urea, ammonia, etc. When these substances come into contact with silver and copper in **jewelry, they produce a chemical reaction to produce silver chloride and copper sulfide, and present deep black chemical salts. This chemical salt often falls from the jewelry, contaminating the wearer's and leaving a very obvious black stain on the jewelry.

At present, cosmetics have also become one of the indispensable "roles" in people's lives. If it is applied to the wearing part of the jewelry, it will undoubtedly provide an opportunity for cosmetics containing chemicals and the jewelry that is most afraid of chemical erosion, and the results can be imagined. Some cosmetics also contain some fine hard particles, which can constitute another type of dirt, thus abrasion ** jewelry.

Regional environmental factors may also make ** jewelry lose its bright color. For example, in drier areas, the air contains more original fine dust, which will form a kind of "human sandpaper" after being contaminated with the human body, which can abrasive the ** jewelry into very fine debris, and local black stains.

It is worth mentioning that talcum powders or moisturizers also contain similar particles, which can also eclipse ** jewelry like the above.

**The surface will oxidize with the oxygen in the air for a long time, but as long as you wipe it with a cloth or something, it will become bright immediately, if you don't have it, then it's fake.

**The reddish color is caused by oxidation due to insufficient gold content.

According to the national standard naming regulations, the content of pure gold jewelry is more than 990%, and the content of pure gold jewelry in Qianlun Cave is more than 999%, and the gold content is not 100%.

This means that although they are high in content, they may contain other impurities. **Jewelry may have red spots on the surface if it is prevented for a long time in a sulfur-containing environment. In addition, when the jewelry comes into contact with acid, there may also be red spots, which are all the result of the oxide layer on the surface of the jewelry due to the oxidation of the impurity elements inside it.

The chemical reaction between a substance and oxygen is a type of oxidation reaction; Oxygen can react chemically with many substances. The function of gaining electrons is called reduction. Oxidation in the narrow sense refers to the combination of substances and oxidation; Reduction refers to the action of a substance losing oxygen.

The oxidation value increases during oxidation; The oxidation value decreases when reduced.

Oxidation, reduction both refer to reactants (molecules, ions, or atoms). Oxidation is also known as oxidation or oxidation reaction. When organic matter reacts, the effect of introducing organic matter into oxygen or removing hydrogen is called oxidation; The action of introducing hydrogen or losing oxygen is called reduction.

The oxidation of a substance that reacts slowly with oxygen and slowly heats up without emitting light is called slow oxidation, such as metal rust, biological respiration, etc.

When gold encounters mercury, it will be colored, and a chemical reaction called bian amalgamation will occur, forming a new substance, gold amalgamation. And the color of gold amalgam is yellow-white, which is attached to the **jewelry, and it feels like the **jewelry is fading.

** Stable properties generally do not react with other substances, even at high temperatures. But ** will react with mercury to form gold amalgamation, which is white, and burning it will turn back into gold.