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Delphi Metals

Understanding Metal Stamps

 

Understanding Metal Stamps

Most jewelry items made of precious metal are stamped with information about the purity level of the metal content. Generally the stamp is placed in an inconspicuous place on the item so it does not detract from the design. Stamps will usually be located on the inside of the band on a ring, on the post or basket setting on a pair of earrings, on the bail (the part that the chain slides through) on a pendant, and on the connecting ring or the clasp on a necklace or bracelet. All jewelry stamps adhere to strict guidelines set by the Federal Trade Commission.

The table below lists the most common precious metal stamps, their alternative stamps or hallmarks, their purity level, and alloys commonly used.

 

Metal Stamps
Metal stamp Minimum percentage of pure metal Common alloys**
.925 Sterling Silver
Also: 925 Sterling, Sterling Silver*
92.5% pure fine silver Usually copper

10k
Also: 16, 417, 10KP*

41.6% pure gold (10 parts out of 24) Usually silver, copper, zinc, and nickel

14k
Also: 583, 585, 14KP*

58.3% pure gold (14 parts out of 24) Usually silver, copper, zinc, and nickel

18k
Also: 750, 18KP*

75% pure gold (18 parts out of 24) Usually silver, copper, nickel, and palladium (for white gold)

22k
Also: 916, 917*

91.6% pure gold (22 parts out of 24) Usually silver and copper

24k
Also: 999*

100% pure gold (24 parts out of 24) None

900 Platinum
Also: 900 Plat, Plat 900, Pt900, 900Pt*

90% pure platinum (900 parts out of 1,000) Ruthenium, rhodium, palladium, and other platinum group metals

950 Platinum
Also: PLAT, PT, 950 Plat, Plat 950, Pt950, 950Pt*

95% pure platinum (950 parts out of 1,000) Ruthenium, rhodium, palladium, and other platinum group metals

*Alternate stamp or European hallmark
**May vary depending on desired color, such as white gold or rose gold

Additional Information

  • The term "karat" (usually abbreviated as "k," "K," or "Kt") refers to the relative purity of gold; pure gold is 24 karats. "Karat" is different from "carat," which is a metric unit of weight for gemstones.
  • In the context of gold jewelry, "plumb" is an old-fashioned term that means that the fineness or purity level of the gold content is precisely what is stamped on the item. The word "Plumb" or the letter P still sometimes follows the metal stamp (e.g. "14k Plumb," "14KP").