Jewelry Hallmarks & Stamps Explained

What Are Jewelry Hallmarks?

Jewelry hallmarks are small stamps or engravings pressed into precious metal items that indicate the metal type, purity, maker, and sometimes the date and place of manufacture. These marks are not decorative — they are legally mandated guarantees of metal content that protect consumers from fraud and misrepresentation. When you see a hallmark on a ring, bracelet, or necklace, you are looking at a verified certificate of what the metal actually is.

The practice of hallmarking dates back to 14th century London, where Goldsmiths' Hall on Foster Lane became the official testing center for gold and silver. Pieces brought to the Hall were assayed (tested for purity), and those that met the required standard were stamped with an official mark — hence the term “hallmark.” The system spread throughout Europe and remains in use today, with many countries maintaining compulsory hallmarking laws.

Understanding hallmarks matters whether you are buying, selling, or inheriting jewelry. For buyers, hallmarks confirm that you are getting what you pay for. For sellers, they determine your item's melt value and help buyers verify authenticity quickly. If you are trying to how to tell if gold is real, hallmarks are the first and most important thing to check.

Hallmarks are found in discreet locations on jewelry: inside the ring shank, on the tongue of a bracelet clasp, on the reverse of a pendant, near the post of an earring, or on the bail of a necklace. They are intentionally small and placed where they do not interfere with the design. A jeweler's loupe (10x magnification) is the standard tool for reading them clearly.

Gold Purity Stamps

Gold purity is expressed in two systems: the karat system (used primarily in the United States) and the millesimal fineness system (used throughout Europe and internationally). Both communicate the same information — what percentage of the alloy is pure gold — just in different formats. The karat system divides gold on a scale of 1 to 24, where 24 karat is pure gold. The fineness system expresses purity in parts per thousand, so 750 means 750 out of 1,000 parts are pure gold (75 percent).

Knowing the purity stamp on your gold is essential for calculating its value. You can use our gold value calculator to get an instant melt value estimate based on the karat and weight of your piece. Here is a comprehensive reference table for gold purity stamps found on jewelry worldwide.

In the United States, the Federal Trade Commission requires that any item marked with a karat value must be within 0.5 karat of the stated purity. An item stamped 14K must test at 13.5K or higher. Items below 10K cannot legally be sold as “gold” in the US. In the UK and several EU countries, hallmarking is compulsory — it is illegal to describe an item as gold, silver, or platinum without an assay office hallmark.

Silver Purity Stamps

Silver purity is almost always expressed using the millesimal fineness system rather than karats. The most common stamp you will encounter is 925, which denotes sterling silver — the global standard for silver jewelry and silverware. Unlike gold, where multiple karat levels are widely used, most silver jewelry falls into just a few categories.

Sterling silver (925) is an alloy of 92.5% pure silver and 7.5% other metals, usually copper, added for strength and durability. Pure silver is too soft for most jewelry applications, which is why sterling became the industry standard. Britannia silver (950) was mandated in England from 1697 to 1720 and is still used for some decorative pieces. Coin silver (900) was the standard for US silver coinage before 1964 and appears on antique American flatware. European continental silver (800) is common on antique silverware and jewelry from Italy, Germany, and Scandinavia.

Platinum Purity Stamps

Platinum is denser and more valuable per gram than gold, and its hallmarking system reflects the different alloy standards used in jewelry manufacturing. Most modern platinum jewelry is stamped Pt950 or 950, meaning 95% pure platinum. Older and vintage pieces may carry different marks. Here is the full reference.

The “IRID PLAT” stamp is unique to mid-20th century American jewelry and indicates a platinum-iridium alloy — 90% platinum and 10% iridium. Iridium was added for hardness and workability. This stamp is commonly found on engagement rings and wedding bands from the 1940s through the 1970s. Despite not carrying a numeric fineness stamp, IRID PLAT jewelry is genuinely high-purity platinum and has significant scrap value. In the US, the FTC requires that any item labeled “platinum” must contain at least 50% platinum by weight, and items marked simply “Platinum” or “Plat” without a fineness number must be at least 95% pure.

Non-Solid Gold Stamps: What to Watch Out For

Not every gold-colored stamp indicates solid gold. Several abbreviations denote items that have a gold surface layer over a base metal core. These items look like gold but contain far less precious metal, and their scrap value is a fraction of solid gold — or in some cases, virtually nothing. Understanding these stamps is critical if you are trying to determine if your gold is real or evaluating inherited jewelry.

The key distinction is between solid gold (10K, 14K, 18K, 22K, 24K) and everything else. Gold-plated (GP) items have an electrochemically deposited gold layer that is typically only 0.5 to 2.5 microns thick — so thin that it wears away with regular use. These items have no meaningful scrap gold value. Gold-filled (GF) items have a substantially thicker layer of gold that is mechanically bonded (pressed) to the base metal. A piece stamped “1/20 14K GF” contains 1/20 of its total weight in 14K gold. On a 20-gram piece, that means about 1 gram of 14K gold, which at 58.5% purity yields only 0.585 grams of pure gold. While GF items do have some scrap value, most gold buyers will not purchase them or will offer very little.

If you find any of these stamps on your jewelry, it is not solid gold. For accurate testing methods beyond hallmark inspection, see our guide to gold purity testing methods.

Where to Find Hallmarks on Jewelry

Hallmarks are deliberately placed in inconspicuous locations so they do not interfere with the appearance of the piece. If you do not know where to look, you can easily miss them. Here is where to check for each type of jewelry.

Rings: Inside the band (the shank). Hold the ring up to the light and look inside the curved surface. Stamps are usually on the flat interior near the bottom of the band. Wide bands may have stamps further inside where the surface is flatter.

Bracelets and chains: On the clasp tongue, the clasp plate, the end link, or a small tag soldered near the clasp. On link bracelets, also check the inside surface of the largest link. Toggle clasps typically have the stamp on the bar or on the ring component.

Earrings: On the post (the pin that goes through the ear), on the back plate (the flat base of stud earrings), or on the omega/clutch back. Hoop earrings are usually stamped near the hinge or clasp mechanism. Drop earrings may have stamps on the top finding or on the connecting jump ring.

Pendants and lockets: On the bail (the loop at the top that the chain passes through) or on the reverse side of the pendant. Lockets are often stamped inside the case, visible when opened. Larger pendants may have stamps on the edge or rim.

Watch cases: Inside the caseback, which typically screws or snaps off. On vintage watches, stamps may also appear on the inside of the case between the lugs, or on the inner surface of the bezel. Note that the watch movement and case are often made by different manufacturers, so the caseback stamp indicates the metal of the case, not the movement.

A 10x jeweler's loupe is the best tool for reading hallmarks. These are inexpensive (under $10) and available at any jewelry supply store. A magnifying glass or the macro mode on a smartphone camera can also work, but a loupe provides the clearest view of small, stamped characters.

Maker's Marks and Date Letters

Beyond purity stamps, jewelry often carries additional marks that identify who made it and when. These marks are especially important for selling antique jewelry, where provenance and age significantly affect value beyond mere metal weight.

Maker's Marks

A maker's mark (also called a sponsor's mark) is a unique symbol or set of initials registered to a specific manufacturer, jeweler, or brand. In the UK, every item submitted for hallmarking must carry a registered maker's mark. In the US, maker's marks are voluntary but common — established brands like Tiffany & Co., Cartier, and David Yurman all use distinctive maker's marks. Identifying a maker's mark can significantly increase the value of a piece beyond its scrap metal content, as branded and collectible jewelry commands a premium.

Date Letters

The date letter system is primarily a British and European tradition. Each assay office uses a cycle of alphabet letters in specific fonts and shields to indicate the year an item was hallmarked. For example, a lowercase “a” in a particular shield shape might indicate 1956 at one assay office but a different year at another. Date letter charts are published by each assay office and are essential for dating British silver and gold. This system has been used continuously since the 15th century, making it one of the oldest consumer protection systems in the world.

Assay Office Marks

In the UK, each assay office has its own distinctive symbol stamped alongside the purity mark and date letter. Learning to recognize these tells you where the piece was tested and certified. The major UK assay office marks are: the leopard's head for London, the anchor for Birmingham, the rose for Sheffield, and the castle for Edinburgh. International assay marks vary by country — France uses an eagle's head for 18K gold, the Netherlands uses a key symbol, and Switzerland uses a St. Bernard dog. These marks are invaluable for identifying the origin of antique and vintage pieces.

Reading Worn or Unclear Stamps

Antique and vintage jewelry often has hallmarks that are partially worn, rubbed smooth, or filled with dirt and polishing compound. Decades of wear can erode the fine details of stamped characters, making them difficult to read even with magnification. This is especially common on rings (which experience the most abrasion) and on the clasps of frequently worn bracelets and necklaces.

Clean the area first. Use a soft toothbrush with warm, soapy water to gently clean around the hallmark area. Decades of accumulated grime often fill in the stamped characters, making them appear shallower than they actually are. After cleaning, dry the piece thoroughly and re-examine under magnification. You may be surprised how much more detail becomes visible.

Use proper magnification. A 10x loupe is standard, but for severely worn stamps, a 20x or 30x loupe or a USB digital microscope can reveal details invisible to the naked eye. Angle the light source to create shadows in the stamped indentations — raking light across the surface at a low angle is the most effective technique for reading faint stamps.

When stamps are illegible, get professional testing. If you cannot read a hallmark despite cleaning and magnification, do not guess. An unreadable stamp does not necessarily mean the piece is not precious metal — it may simply be very old or heavily worn. A professional jeweler or pawnbroker can use acid testing, electronic gold testers, or X-ray fluorescence (XRF) analyzers to determine the metal type and purity accurately, regardless of stamp condition. Learn more about these methods in our guide to gold purity testing methods.

One important note: the absence of a hallmark does not automatically mean an item is fake or base metal. Some countries and time periods did not require hallmarking. Many Native American silver pieces, antique Asian gold pieces, and some handmade artisan jewelry are unmarked but genuine. Conversely, the presence of a hallmark is not an absolute guarantee of authenticity — counterfeit stamps do exist, particularly on items from unregulated markets. When significant value is at stake, always verify with professional testing.

Frequently Asked Questions

What does 750 mean on jewelry?

The stamp 750 means the piece is 18 karat gold, containing 75.0% pure gold. The number refers to millesimal fineness — 750 parts per thousand are pure gold. The remaining 25% consists of alloy metals (typically copper, silver, or zinc) added for strength, durability, and color. 18K/750 is the standard for fine European jewelry and is widely used in high-end pieces from brands like Cartier, Bulgari, and Van Cleef & Arpels. Use our gold value calculator to see what 18K gold is worth per gram at today's prices.

What does 925 mean on gold-colored jewelry?

A 925 stamp on gold-colored jewelry indicates the piece is sterling silver (92.5% pure silver) with a gold surface treatment. This is usually either gold plating (a thin electrochemical coating) or gold vermeil (a thicker gold layer over sterling silver, at least 2.5 microns by FTC standards). The 925 stamp refers to the silver base, not gold. Real solid gold is stamped with karat marks such as 10K, 14K, 18K, or 24K, or with fineness numbers such as 417, 585, 750, or 999. If your gold-colored piece is stamped 925, the gold is only a surface layer and the item's value is based on its silver content.

How do I know if my jewelry is real gold or gold-plated?

The fastest method is checking the hallmark stamps. Solid gold carries karat stamps (10K, 14K, 18K, 22K, 24K) or fineness numbers (417, 585, 750, 916, 999). If you see GP, GEP, HGE, or RGP, the item is gold-plated. If you see GF or a fraction like 1/20 14K GF, it is gold-filled — better than plated but still not solid gold. Beyond stamps, look for areas where the gold color has worn away to reveal a different color underneath (typically grey or green), which is a telltale sign of plating. For definitive results, have the piece tested with acid or an electronic gold tester at any jeweler or pawnbroker — most offer free testing. For more methods, see our complete guide on how to tell if gold is real.

What does GF mean on a jewelry stamp?

GF stands for Gold Filled. Gold-filled jewelry has a thick layer of gold mechanically bonded (heat-pressed) to a base metal core, usually brass or copper. By FTC standards, the gold layer must constitute at least 1/20 (5%) of the item's total weight. A typical stamp reads “1/20 14K GF,” meaning 5% of the total weight is 14-karat gold. Gold-filled pieces are significantly more durable than gold-plated items and can last decades without wearing through, which is why vintage gold-filled jewelry is still common. However, a gold-filled item contains far less gold than a solid gold piece of the same weight. A 20-gram item stamped 1/20 14K GF contains only about 1 gram of 14K gold (0.585 grams of pure gold), compared to 11.7 grams of pure gold in a 20-gram solid 14K ring. Most scrap gold buyers do not purchase gold-filled items, or offer very little for them.

Hallmarks are the first thing any buyer checks when evaluating jewelry. Understanding what those tiny stamps mean puts you in a stronger position whether you are buying, selling, or simply curious about a family heirloom. If you are ready to find out what your gold jewelry is worth based on its hallmark and weight, use our free gold value calculator for an instant estimate based on today's live spot price.