1, pure gold: that is, the gold content is not less than 990, and the marks are "pure gold", "gold 990", "G990" and "AU990".
2. Thousands of pure gold: that is, the gold content is not less than 999, and the marks are "Jin 999", "G999" and "AU999".
3.k gold: colored gold, which refers to precious metals with a gold content between 8K and 24K. 18K gold has a gold content of 750‰ and is marked as "750" and "18K". 14K gold has a gold content of 585‰ and is marked as "585" and "14K".
Extended data
Maintenance method of gold jewelry
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.
Reference source? Baidu encyclopedia-gold jewelry