925 sterling silver means silver with 92.5% purity, internationally recognized standard for fine silver. 100% silver is too flexible to shape up and apt to “oxidation”, known as “discoloring”.
Plain silver: 925 sterling silver is plated with white rhodium coating (Which is called platinum in jewelry industry), which maximally delays the fading and blackening of silver under the condition of oxidation or sulfuration. Industrially, 925 sterling silver not plated with white rhodium coating is called plain silver, which is apt to oxidation when exposed in the air. A large portion of 925 sterling silver commercially available on the market is plain silver for reduction of cost.
Thai silver: a kind of product that is special in Thai market, with the same standard content as 925 sterling silver. Thai silver features matt surface for obtaining the effect of “ancient” and “old” “aged silver”. Thai silver is a bit higher in price than 925 sterling silver, because Thai silver is more expensive in labor cost.
Tibet silver: Generally, it does not contain silver, but an elegant name of cupronickel (Copper-nickel alloy); traditional Tibet silver is composed of 30% silver and 70% copper, even this kind of “Tibet silver” made by traditional process is rare in current market, and most Tibet silvers are fully substituted by cupronickel. Various types of vivid counterfeits: these fake silvers are plated with a silver coating to deceive the customers. When they’re appraised by jewelry appraisal organization, it’s likely to be mistakenly judged as authentic silver jewelry due to the reason that the 999 silver or 925 sterling silver coating is only appraised,. It’s recommended that, when appraising silver jewelry, the most reasonable method is to cut a section from middle part, and test the central part of the sample.