925 pure silver means 925/1000 pure silver. It's like 999 gold. Because whole silver is too soft and easily oxidized, Tiffany & Co. created the formula for 925 sterling silver.

　　Silver is an active metal that tends to react with sulfur in the air, turning the silverware black. Therefore, when wearing as little as possible and air contact, should not be in the chemical gas concentrated place wearing. After contact with the sulfur soap, it must be dried immediately. Chloride in sweat can also affect silver.

　　Due to the characteristics of silver itself, the 100% silver is very soft, easy to scratch, and not suitable for more and more sophisticated technology requirements, as well as modern popular jewelry more and more rich and exaggerated modeling requirements. This, combined with the fact that 100% silver tends to change color and lose luster, led to the rapid emergence of 925 sterling silver as the mainstay of silver jewelry after Tiffany introduced the first silverware containing 92.5% silver in 1851

　　Due to the addition of 7.5% alloy, silver has the ideal hardness, brightness and luster, and oxidation resistance. And can inlay all kinds of gemstones, diamonds, jade and hao stone, since then silver jewelry with bright color, chic style, exquisite workmanship of the fashion taste in the middle price, quickly swept the world, become a new generation of leaders in the fashion industry.