Precious Metal Stamps - Hallmarking

Meaning of Precious Metal Stamps

Metal stamp | Minimum percentage of pure metal | Common alloys**

.925 - Also 925 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

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").

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