Gold

• A 24-karat or 999 stamp is 100 percent pure gold. Standard karat marks include 22k or 916 (91.6% gold), 18k or 750 (75%), 14k or 585 (58.5%) and 10k or 417 (41.6%). Many countries use these stamp hallmarks and may also have stamps of their own, which is a good indication of where the jewelry was made as well as its precious metal content.
  
  

Silver

• Sterling silver is stamped 925 Sterling Silver or simply .925 and is 92.5% fine silver. Much vintage jewelry will have stamps below 925, a common one being 800. Foreign countries commonly use symbols for silver stamps.
  
  

Platinum

• Platinum is marked either 900 Platinum and is 90 percent pure or 950 Platinum and is 95 percent pure. Other stamps with the numbers may include Plat, or Pt.
  
  

Symbol Hallmarks

• Some country jewelry stamp marks include a walking lion used in England, the thistle for Scotland or a boar's head for France. Taxco 980 is a silver mark out of Mexico.
  
  

Tips

• Some vintage or custom-made jewelry may not bear a hallmark stamp. In that case, the jewelry item should be tested by a reputable jeweler to determine its precious metal content.