1. China's national standard GB 1 1887-89 stipulates that the gold content per k is 4. 166%, and the minimum purity of 14K is 585, that is, it is not allowed to be lower than 58.5%. Therefore, since ancient times, most pure gold has been mixed with other metals to make gold ornaments, which are called "decorative gold".
2. Gold ornaments are decorated with various K numbers and colors. When gold is mixed with copper, silver, nickel and palladium with different specific gravity, it is green. Au-Ag-Cu(-Zn) alloy is the most commonly used colored gold alloy in ornaments. Platinum alloys are mostly Au-Ag-Ni(Cu, Zn) and Au-Ag-Pd(-Zn, Cu) alloys. Reducing the proportion of aluminum forms purple gold, whose lavender is quite charming and fragile, and it is difficult to process.
3. The basic component of blue K gold is the alloy of gold and iron, but its production process is extremely confidential, and patents have been registered all over the world. Depending on the species, cobalt atoms are implanted into the surface of K gold.