Science, Tech, Math › Science Metal Jewelry Stamps and Marks Quality marks reveal metal composition Share Flipboard Email Print Dorling Kindersley/Getty Images Science Chemistry Chemistry In Everyday Life Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated February 12, 2020 Jewelry made from precious metals is often stamped with a mark to indicate the chemical composition of the metal. A quality mark contains information about metal content that appears on an article. It is usually stamped or inscribed on the piece. There is considerable confusion about the meaning of quality marks that are seen on jewelry and other items. Here is some information that will demystify terms such as "plated," "filled," "sterling," and others. Gold Quality Marks karat, carat, Karat, Carat, Kt., Ct., K, C Gold is measured in karats, with 24 karats being 24/24ths gold or pure gold. A 10 karat gold item contains 10/24ths gold, a 12K item is 12/24ths gold, etc. Karats may be expressed using a decimal figure, such as .416 fine gold (10K). The minimum allowable quality for karat gold is 9 karats. Karats are not to be confused with carats (ct.), which are a unit of gemstone mass. One carat weighs 0.2 grams (1/5 of a gram or 0.0007 ounces). A hundredth of a carat is called a point. Gold-Filled and Rolled Gold Plate gold-filled, G.F., doublé d'or, rolled gold plate, R.G.P., plaqué d'or laminé The quality mark for gold-filled is used for an article (except optical frames, watch cases, hollowware, or flatware) consisting of a base metal to which a sheet of at least 10 karat gold has been bonded. Additionally, the weight of the gold sheet must be at least 1/20th the total weight of the item. The quality mark may specify the ratio of the weight of the gold in the article to the total weight of the article as well as a statement of the quality of the gold expressed in karats or decimals. For example, a mark of "1/20 10K G.F." refers to a gold-filled article that consists of 10 karat gold for 1/20th of its total weight. Rolled gold plate and gold-filled may utilize the same manufacturing process, but the gold sheet used in rolled gold usually is less than 1/20th the total weight of the article. The sheet must still be at least 10 karat gold. Like gold-filled articles, the quality mark used for rolled gold plate articles may include a weight ratio and a statement of quality (for example, 1/40 10K R.G.P.). Gold and Silver Plate gold electroplate, gold-plated, G.E.P., electroplaqué d'or or or plaqué, silver electroplate, silver plate, silver-plated, electroplaqué d'argent, plaqué d'argent, or the abbreviations of these terms The quality marks for gold-plated indicate that an article has been electroplated with gold of at least 10 karats. The quality marks for silver-plated indicate that an article has been electroplated with silver of at least 92.5% purity. There is no minimum thickness required for silver plated or gold plated articles. Silver Quality Marks silver, sterling, sterling silver, argent, argent sterling, abbreviations of these terms, 925, 92.5, .925 The quality marks or a decimal figure may be used on articles containing a minimum of 92.5% pure silver. Some metals may be called 'silver' when, in fact, they are not (except in coloration). For example, nickel silver (also known as German silver) is an alloy consisting of about 60% copper, about 20% nickel, about 20% zinc, and sometimes about 5% tin (in which case the alloy is called alpaca). There is no silver at all in German/nickel/alpaca silver or in Tibetan silver. Vermeil vermeil or vermil The quality marks for vermeil are used on articles made of silver of at least 92.5% purity and plated with gold of at least 10 karats. No minimum thickness is required for the gold plated portion. Platinum and Palladium Quality Marks platinum, plat., platine, palladium, pall. The quality marks for platinum are applied to articles composed of at least 95% platinum, 95% platinum, and iridium, or 95% platinum and ruthenium. The quality marks for palladium are applied to articles composed of at least 95% palladium, or 90% palladium and 5% platinum, iridium, ruthenium, rhodium, osmium or gold. View Article Sources "Guides for the Jewelry, Precious Metals, and Pewter Industries." Federal Register: The Daily Journal of the United States Government. Federal Trade Commission, 16 Aug. 2018.