The Content of common silver jewelry

1. 999 silver
It contains 99.9% of silver. It is white color and very soft. Usually the jewelry is produced from simple technique. Not suitable for stone setting jewelry. The hallmark is “999”.

"999" silver ring handmade of Silver metal Clay

2. 925 silver
It is the mixture of 92.5% of silver and 7.5% of copper (or other metal). It is also named as Sterling silver. The hallmark is “925”.

"925" silver earrings

3. Thai silver
925 sterling silver with process of oxidizing to make antiqued silver appearance. It is a specialty of Thailand.

Thai silver earrings

4. Tibet silver
Alloy mixed with nickel and copper. It is produced at Tibet and Nepal. Although it is named as silver, it does not contains any silver .

Tibet silver bangle from China

The most common millesimal finenesses used for Silver :

• 
  999.9 (Ultra-fine silver used by Royal Canadian Mint in the Canadian Silver Maple Leaf)
  999 (Fine silver used in bullion bars, also known as three nines fine)
  980 (common standard used in Mexico ca.1930 - 1945)
  958 (equivalent to Britannia silver)
  950 (equivalent to "French 1st Standard")
  925 (equivalent to Sterling silver)
  900 (equivalent to "Coin silver" in the USA, also known as one nine fine)
  875 (could be found in former USSR and in Switzerland)
  833 (common standard used in continental silver especially among the Dutch, Swedish, and Germans)
  830 (common standard used in older Scandinavian silver)
  835 (a standard predominantly used in Germany after 1884)
  800 (minimum standard for silver in Germany after 1884; Egyptian silver; Canadian silver circulating coinage)
  750 (uncommon silver standard found in older German, Swiss and Austro-Hungarian silver)
  ( REF: Wikipedia )