Jewelry Hallmarks Guide: Gold, Silver & Platinum Stamps

What a Jewelry Hallmark Can and Cannot Tell You

A complete hallmark may include a purity mark, a maker's mark, an assay office mark, a date letter, an import mark, or a special national symbol. Modern jewelry often has only a purity stamp such as 14K, 925, or PT950, while older British and European pieces may have several tiny symbols grouped together.

The purity mark gives the most direct metal clue: it indicates the proportion of precious metal in the alloy. It does not automatically prove the gemstone is natural, confirm the designer, establish the age, or provide a market value. For insurance, resale, estate division, or suspected high-value jewelry, a professional jeweler, appraiser, or gemologist should inspect the piece in person.

• Purity marks identify metal content, such as 750 gold or 925 silver.
• Maker's marks identify a manufacturer or sponsor, but many are reused, similar, or hard to trace.
• Assay marks indicate that a recognized office tested the metal in certain countries.
• A stamp is evidence, not proof; testing may still be needed.

Gold Stamp Meanings: Karats, Millesimal Numbers, and Plating

Gold jewelry is commonly marked by karat in the United States and by millesimal fineness in many international systems. 24K or 999 means nearly pure gold, 22K or 916 means about 91.6% gold, 18K or 750 means 75% gold, 14K or 585 means 58.5% gold, 10K or 417 means 41.7% gold, and 9K or 375 means 37.5% gold. Some older or regional pieces may use 416 for 10K or have unusual spacing, such as 14 KT or 18ct.

Gold-filled, gold-plated, and electroplated pieces have different meanings than solid gold. Marks such as GF, 1/20 12K GF, RGP, HGE, GP, GEP, and gold overlay usually indicate a base metal core with a layer of gold. Vermeil normally means gold over sterling silver, but the thickness and legal requirements vary by country and period.

White gold, rose gold, and yellow gold can all carry the same purity numbers because color is created by alloy metals. Nickel, palladium, copper, silver, and zinc can change color and durability, so a 14K white gold ring and a 14K rose gold ring have the same gold proportion but different alloy recipes.

• 999 or 24K: very high-purity gold, usually softer than lower-karat alloys.
• 750 or 18K: common fine jewelry standard with high gold content.
• 585 or 14K: common in the United States for rings, chains, and earrings.
• GF, GP, HGE, RGP: not solid gold; these usually indicate layered or plated jewelry.

Silver Hallmarks: Sterling, Coin Silver, and Silverplate

The most common modern silver mark is 925, which means sterling silver: 92.5% silver alloyed with other metals, usually copper. You may also see STERLING, STER, STG, or .925. Higher-purity silver marks include 950, 958, and 999, while lower European silver standards can include 800, 830, 835, and 900.

Coin silver usually refers to silver around 900 fineness, especially in older American pieces, but the term can be used inconsistently. A stamp reading COIN, PURE COIN, or 900 should be evaluated with the object's age, construction, and maker context. Decorative hollowware and flatware may have different marking conventions than rings and necklaces.

Silverplate marks are often misunderstood. EPNS means electroplated nickel silver, which is not solid silver; nickel silver is a copper-nickel-zinc alloy with no actual silver unless plated. Other plate-related marks include EP, E.P., A1, Quadruple Plate, Silver on Copper, and IS on many twentieth-century flatware pieces. These can look bright and attractive but usually have much lower metal value than sterling.

• 925, STERLING, or STER: usually sterling silver.
• 800, 835, 900, 950: silver standards used in various regions and eras.
• EPNS, EP, A1, Quadruple Plate: usually silverplate, not solid silver.
• Tarnish supports the possibility of silver but does not prove sterling quality.

Platinum and Palladium Stamps: PT, PLAT, 950, and Alloy Codes

Platinum jewelry is often stamped PLAT, PT, PLATINUM, 950PT, PT950, 900PT, or 850PT. A 950 platinum stamp generally means the piece is 95% platinum by weight, while 900PT means 90% platinum. Platinum is dense, durable, and naturally white, so it often feels heavier than similarly sized gold or silver jewelry.

Many platinum marks include alloy abbreviations such as IRID, IR, RU, or PD, indicating iridium, ruthenium, or palladium in the alloy. For example, 950Pt/Ru generally means 95% platinum with ruthenium as a significant alloy metal. These alloy details can affect hardness, workability, and repair approach, so they matter to jewelers even when the piece looks the same to the eye.

Palladium is a separate precious metal and may be marked PD, PALL, PALLADIUM, or 950PD. It is also naturally white and can be mistaken for platinum, but it is typically lighter. If a stamp is unclear, a bench jeweler can use XRF testing or other professional methods to distinguish platinum, palladium, white gold, and silver without relying on appearance alone.

• PT950 or 950 PLAT: common high-purity platinum jewelry mark.
• PT900 or 900 PLAT: platinum alloy with 90% platinum.
• IR, RU, PD after a platinum mark: alloy clues, not brand names.
• PD950: palladium, not platinum.

Where to Look for Hallmarks on Rings, Chains, Watches, and Earrings

Hallmarks are usually placed where they are protected from wear but still accessible. On rings, check the inside of the band, especially near the base of the shank. On necklaces and bracelets, inspect the clasp, jump rings, end tabs, safety chains, and small plaques near the closure. On earrings, marks may be on posts, backs, hoops, or the inner curve.

Watches and lockets can be more complicated because cases, movements, bezels, and bracelets may be made by different manufacturers or replaced over time. A gold-filled watch case, a stainless steel case back, and a solid gold bracelet can all appear on the same item. Always identify which component carries the stamp before assuming the whole object is the same metal.

Use a 10x jeweler's loupe, bright side lighting, and a clean microfiber cloth to read small marks. Avoid aggressive polishing before inspection because it can remove patina, soften edges, and make shallow stamps harder to read. If a mark looks like 585 in one angle and 985 in another, photograph it from several directions before drawing a conclusion.

• Rings: inside shank or near resizing areas.
• Chains: clasp, tag, end cap, or jump ring.
• Earrings: post, back, hinge, or inner hoop.
• Watches: case back, inside case, bracelet clasp, and lugs may differ.

How to Read Multiple Marks Together

The most reliable interpretation comes from reading marks as a set. A ring stamped 750 with a maker's punch and an assay symbol tells a stronger story than a loose 18K stamp by itself. Conversely, a chain marked 14K on the clasp but not on the links may require closer inspection because clasps are commonly replaced.

Country systems vary. British hallmarks may include an assay office symbol, sponsor's mark, metal fineness, and date letter. French gold and platinum pieces often use small pictorial control marks, while Italian jewelry commonly shows a fineness mark plus a manufacturer registration number and province abbreviation. Scandinavian, German, Mexican, and American marks each have their own conventions.

Do not force a mark into the first match you find online. Many letters and symbols look similar at tiny scale, and maker's mark databases can contain multiple companies with overlapping initials. Match the metal mark, construction, style, country clues, and wear patterns before treating a maker attribution as likely.

• Read purity, maker, assay, and import marks together.
• Check whether the marked component is original to the piece.
• Compare mark shape, not just letters.
• Treat online maker matches as leads until verified.

When Stamps Are Missing, Wrong, or Not Enough

Some genuine jewelry has no visible stamp because it was handmade, resized, repaired, worn thin, imported before modern marking rules, or produced in a region with different requirements. A missing mark does not automatically mean fake or low quality. It simply means you need other evidence.

A stamp can also be misleading. A base metal item can be fraudulently stamped 18K, a plated piece can lose its plating and expose a different metal, and a ring can retain an old mark after repair or resizing. Acid testing, electronic testers, density checks, and XRF analysis can help, but each has limits and should be performed carefully to avoid damage.

For valuable, inherited, or gem-set jewelry, the best next step is a hands-on inspection. A professional can test metal content, inspect solder seams, evaluate stones, check for treatments, and document condition. Hallmarks are the starting point, not the final verdict.

• No stamp can still be genuine precious metal.
• A stamp can be counterfeit or placed on a replaced component.
• Gemstone identity is not proven by a metal hallmark.
• Use professional testing before selling, insuring, or altering valuable jewelry.