The blackening of gold jewelry is inseparable from human sweat. If you are careful, you will find that jewelry changes color more in summer than in winter. This is because the metabolism of the human body is fast in summer, and about 1% of the sweat discharged is wastes in the human body, such as chlorinated substances, urea and ammonia. These elements react with silver or copper in gold jewelry to produce silver chloride and copper sulfide, and there will be associated dark black chemical salts on the skin.

It's not directly related to purity, so don't worry.

Extended data:

gold ornaments

Gold jewelry refers to jewelry made of gold as the main raw material. The chemical symbol of gold is Au, with a specific gravity of 17.4 and a Mohs hardness of 2.5. Gold ornaments can be divided into pure gold and k gold according to their gold content.

The gold content of pure gold jewelry is above 99%, and the highest can reach 99.99%, so it is also called "99 gold", "all gold" and "red gold". In order to overcome the shortcomings of gold, such as high price, low hardness, single color, easy wear and delicate pattern, some other metal elements are usually added to pure gold to increase the hardness of jewelry gold, change its color tone and lower its melting point, so that gold alloy jewelry with different colors and obviously different gold contents appears, and is marked with the word "Kai".

K-gold system is an internationally accepted standard of gold measurement. The complete characterization of K-gold is "K-gold", which gives K-gold an accurate gold content standard, thus forming K-gold jewelry series.

Maintenance method

1, cleaning chemicals will change the color of gold, so take off the gold ornaments before cleaning.

2. Avoid direct contact with volatile substances such as perfume and hair gel, otherwise it will easily lead to the fading of gold ornaments.

3. Take off the gold ornaments when swimming to avoid chemical changes on the surface after contact with seawater or pool water.

4. Wrap it in flannel and put it in a jewelry box when keeping it to avoid mutual friction and damage.

5. Gold is soft and easy to deform. Do not pull necklaces and other accessories to avoid deformation.

6. Pure gold jewelry will react chemically when it encounters mercury, and white spots will appear. When cleaning, as long as you barbecue under the alcohol lamp for a while, it will return to its original color.

7. After wearing, gold ornaments often lose their luster due to stains and dust. At this time, just put the gold ornaments in a neutral detergent, soak them in warm water, and then take them out and dry them.

References:

Baidu encyclopedia-gold jewelry