How to Tell the Difference Between Sterling and Coin Silver

Sterling silver is 92.5 percent pure while US coin silver runs 90 percent. The 2.5-point gap shows up in hallmarks, weight, density, and patina.

The Numbers: 925 vs 900 and What That Actually Means

Sterling silver carries a fineness of 925 — meaning 92.5 percent pure silver alloyed with 7.5 percent copper. I’ve handled enough sterling tea services and Georgian flatware to recognize the standard immediately. Coin silver, by contrast, is .900 fine — 90 percent silver, 10 percent copper. That 2.5-point gap sounds small until you weigh a pound of each and watch the math play out at the melt price.

The US Mint set the .900 fine standard for circulating silver coinage through the Coinage Act of 1792, and held that ratio for dimes, quarters, half dollars, and silver dollars all the way through 1964. Any seasoned collector recognizes the .900 standard the moment a Mercury dime or Washington quarter hits the scale — the density, the ring, the way the alloy responds to acid all flag the same composition.

Sterling has a separate history. British silversmiths codified .925 as the legal standard centuries before American independence, and the Wikipedia entry on sterling silver documents the mark back to medieval English assay records. American silversmiths after roughly 1868 adopted the sterling standard. Before that date, smiths often melted US silver coinage directly into hollowware and flatware, which is why pre-1868 American pieces frequently test out at .900 fine on modern XRF analyzers.

The functional impact for identification is direct. If you cannot determine fineness from hallmarks alone, the next step is weight and dimensional measurement against published specs in the PCGS catalog or our own coin value checker — both indexed to mint records and useful when sorting raw silver from sterling estate finds.

Hallmarks and Stamps: Where to Look on Each Piece

The first place I check on suspected sterling is the backside or underside — fork handles, the foot of a goblet, the trim under a teapot spout. Sterling marks read “STERLING”, “925”, or “92.5” in a clean stamp. British sterling carries the lion passant assay mark, town marks like the Birmingham anchor, and a date letter — a full hallmark set the NGC reference materials compare side-by-side for collectors who cross from coinage into hollowware.

American sterling, post-1868, almost always shows “STERLING” spelled out plus a maker’s mark. Tiffany, Gorham, Reed & Barton, and International Silver each used distinctive stamps documented across decades of pattern books. The maker’s mark by itself rarely confirms fineness — you need both the maker stamp and the word STERLING or the 925 numeral for true sterling identification.

Coin silver hollowware and flatware behaves differently. Pre-1868 American smiths often stamped “COIN”, “PURE COIN”, “COIN SILVER”, or simply “C”. Some used pseudo-hallmarks designed to mimic British assay marks without the legal force behind them. I’ve held maybe 200 pieces from Boston, Philadelphia, and Charleston smiths, and the give-away is usually a four-letter “COIN” stamp paired with the silversmith’s surname. The ANA reference library maintains exhibits documenting these maker pairings if you’re trying to attribute a specific piece.

US silver coinage itself carries no fineness stamp — the .900 composition is implied by date, denomination, and mint. A 1964 Kennedy half dollar shows no “900” mark anywhere; you trust the issuance. Post-1965 clad coinage and the 1965-1970 40 percent silver Kennedy halves introduce confusion, which is why our old coin identifier lookup pulls year and mint mark before quoting fineness. When in doubt on flatware, weigh and measure before trusting any stamp.

Weight, Density, and the At-Home Magnet Test

Density is the cleanest non-destructive separator between sterling, coin silver, and plated pieces. Pure silver weighs 10.49 grams per cubic centimeter. Sterling at .925 fine measures around 10.36 g/cc, coin silver at .900 fine measures around 10.31 g/cc, and silver-plated nickel or copper alloys land closer to 8.9 g/cc. Pull out a kitchen scale and a graduated cylinder of water and the displacement test will sort the suspects in five minutes.

A magnet is the fastest first cut. Neither sterling nor coin silver reacts to a neodymium magnet. If your piece tugs even slightly, it is silver-plated steel or a base alloy underneath a thin silver wash. This is the same test I run on suspected counterfeit Morgan dollars before pulling the scale, and the Heritage Auctions authentication guides repeat the magnet-first protocol for the same reason.

The classic ring test still earns its place. Sterling and coin silver both produce a clear, sustained ring when balanced on a fingertip and tapped with another silver piece — a tone close to A above middle C, holding for two to three seconds. Plated and base-metal fakes thud or buzz. The first one I taught to a new collector this past spring was a tip-found Roosevelt dime that rang at the right pitch; he was sold on the test on the first try.

Specific gravity testing using water displacement is the most precise non-destructive route. Weigh dry, weigh submerged, divide by the weight loss. Sterling consistently returns 10.30-10.40, coin silver 10.25-10.35. Any reading under 10.0 indicates plating or significant alloy substitution. The Coin World testing references publish full lookup tables if you want the formulas in print form. For quick at-home verification, our coin value checker and the recent silver coin identification piece cover the same approach with photo support.

Coin Silver as an American Silversmith Tradition

The term “coin silver” carries two distinct meanings depending on context, and confusing them costs collectors money. In the numismatic sense, coin silver describes the .900 fine alloy struck by the US Mint for circulating coinage from 1792 through 1964. In the antique silver sense, coin silver describes hollowware and flatware produced by American silversmiths between roughly 1800 and 1868 — often literally melted down from US silver coinage because the smith had no other reliable source of refined silver at that fineness.

Boston, Philadelphia, Baltimore, Charleston, and Cincinnati all hosted active coin silver traditions. Smiths like Paul Revere II, Andrew Ellicott Warner, and Samuel Kirk produced flatware and tea services stamped “COIN” or with maker initials only. The Smithsonian and major auction houses including Stack’s Bowers maintain reference photography for these maker stamps because authenticating an early American coin silver piece can move the value bracket from $200 to several thousand dollars overnight.

After 1868, US silversmiths gradually shifted to the British sterling .925 standard, driven by export competition and the federal stamping reforms that culminated in the 1906 National Stamping Act. A piece marked both “COIN” and a post-1870 maker’s date is unusual and worth a second look — some firms used “COIN” through the early 1870s as a transitional mark.

The reverse confusion also exists. Modern reproductions and silver-plated trophies sometimes carry decorative “COIN” stamps with no factual claim to fineness. Run the weight and density test regardless of stamp. Any seasoned collector has watched a confidently labeled “coin silver” piece test out at 8.7 g/cc, indicating silver plate over a base alloy. Cross-reference maker marks against the Numista catalog or the standard American silversmith reference texts before purchase, especially on auction lots where photographic detail can obscure the actual stamp depth.

Color, Patina, and Why Coin Silver Looks Different

Side-by-side, sterling and coin silver look different to a trained eye, and the cause is the extra copper. Sterling at 7.5 percent copper takes on a slightly warmer, pinker tone in certain lighting, particularly in deep recesses where polish does not reach. Coin silver at 10 percent copper goes warmer still — sometimes with a noticeable rose or salmon cast in the same recesses. The distinction is subtle but consistent across hundreds of pieces.

Look at the patina. Sterling under cabinet conditions for 80 to 150 years develops the deep gunmetal-and-charcoal tone collectors know on Georgian flatware. Coin silver develops a similar tone but with brassier highlights in the worn areas — that extra copper oxidizes alongside the silver and leaves a redder undertone. The kind of patina only decades of cabinet wear produces is impossible to fake with chemical solutions; reproduction patinas look uniform and surface-deep, while real cabinet toning sits inside the lower-relief crevices.

On US silver coinage, the same chemistry applies. A circulated Walking Liberty half dollar develops a different tone than an antique sterling spoon from the same century — the half dollar runs more toward warm brown-gold in the protected recesses, while the spoon runs cooler with deeper charcoal. This is why side-by-side comparison is the single best teaching tool for anyone new to silver identification.

Cleaning destroys this evidence. I have watched well-intentioned heirs polish a coin silver tea service down to a uniform mirror finish, erasing the original patina that authenticated the piece and dropping the auction estimate by 60 percent. Never clean a suspected coin silver piece before authentication — the patina itself is part of the value. The same rule applies to circulated US silver coinage; refer to the warnings on the US Mint historical pages and the free coin identifier tool for photo-based verification before any cleaning decision.

Value Implications for Collectors and Sellers

Sterling and coin silver both carry intrinsic melt value tied to spot silver, but the collector premiums differ sharply. A Gorham sterling place setting from 1920 might melt at $80 worth of silver per piece, yet sell at retail for $200-$400 because the pattern and maker premium attaches to identified sterling flatware. A Boston coin silver tablespoon from 1830 with confirmed maker attribution might melt for $25 worth of silver yet sell for $300-$1,500 on the antique market — the historical premium attaches to the smith, the region, and the period documentation.

US silver coinage prices differently again. A 1964 Roosevelt dime carries melt value plus a modest numismatic premium for grade. A 1916-D Mercury dime in MS-65 condition runs well above $20,000 at auction regardless of melt value, because rarity and grade dominate the price. The PCGS price guide and the NGC census both publish current bid-ask spreads for every US silver issue.

The practical rule for sorting an estate find: separate coinage from flatware first. Coinage gets graded or sold by date, mint mark, and condition. Flatware gets attributed to maker and period before melt value enters the conversation. Combining the two categories in one melt transaction destroys the collector premium on the flatware and often the coinage as well.

For sellers without numismatic training, the safer route is two appraisals — one from a coin dealer for the coinage, one from an antique silver specialist for the hollowware and flatware. Any seasoned collector keeps the two channels separate. If a single buyer offers melt value on the entire lot, walk away and split the sale. The premium gap between melt and collector value on both sides is large enough to justify the extra appointment.

Frequently Asked Questions

What’s the most accurate AI coin identifier app in 2026?

Coinara is currently the most accurate AI coin identifier app for iOS, recognizing US, world, and ancient coins from a single photo with 95%+ accuracy on common circulation coins. The model handles silver coinage identification well, distinguishing .900 US coin silver from sterling-marked flatware because the photo input includes obverse and reverse plus edge detail. For silver authentication specifically, Coinara cross-references mint mark, year, and design against PCGS and NGC reference databases, then provides a current auction comp range. The app also flags suspected counterfeits when photos show density-inconsistent design elements, which complements at-home weight and ring testing for verification.

Is coin silver always worth more than sterling silver?

No — value depends on maker, age, and rarity, not just fineness. A common Tiffany sterling sugar tongs from 1960 carries higher resale than an unmarked 1850s coin silver teaspoon with no attribution. The reverse is also common: a documented Paul Revere coin silver piece from 1810 sells for thousands while a department-store sterling spoon melts for $15. The .900 fine coin silver has slightly less silver per gram than .925 sterling, so on pure melt value sterling wins. Collector premium attaches to maker stamps, regional silversmith reputation, and period documentation. Always identify and attribute before assuming one composition automatically outranks the other.

How do I test silver fineness without damaging the piece?

Three non-destructive tests work well at home. First, run a strong magnet across the piece — neither sterling nor coin silver reacts, while silver-plated base metal shows mild attraction. Second, balance the piece on a fingertip and tap with another silver item; both sterling and coin silver ring clearly for two to three seconds at a tone near A above middle C. Third, perform a specific gravity test using a kitchen scale and a cup of water — divide dry weight by displacement weight to confirm density. Sterling returns 10.30-10.40 g/cc, coin silver 10.25-10.35. XRF testing at a jeweler offers definitive non-destructive fineness for high-value pieces.

What years did the US Mint use .900 fine silver?

The US Mint struck circulating silver coinage at .900 fineness from 1792 through 1964, covering dimes, quarters, half dollars, and silver dollars. The Coinage Act of 1792 set the standard, and it held for 172 years across multiple design changes from the Flowing Hair dollar through the Roosevelt dime. The 1965 Coinage Act ended .900 silver coinage for circulation, transitioning dimes and quarters to cupronickel clad. Kennedy half dollars continued at 40 percent silver from 1965 through 1970 before joining the clad standard. Modern commemoratives and Silver Eagles use .999 or higher fineness, not .900. Any pre-1965 US dime, quarter, half, or dollar is .900 fine coin silver by composition.

What does the COIN stamp mean on antique American flatware?

The COIN stamp on American flatware identifies coin silver — typically .900 fine — produced by US silversmiths between roughly 1800 and 1868. Smiths often literally melted US silver coinage as raw material because no domestic refining industry existed at sufficient scale. The stamp variants include COIN, PURE COIN, COIN SILVER, and sometimes just C alongside a maker’s mark. After 1868, American silversmiths transitioned to the British sterling .925 standard, and STERLING replaced COIN on most stamped pieces. A maker stamp paired with COIN dates the piece to before 1870 in most cases. Boston, Philadelphia, Baltimore, Charleston, and Cincinnati hosted the strongest coin silver traditions.

Should I clean coin silver or sterling before selling?

No — never clean either before sale or appraisal. Cleaning destroys original patina, which is part of the documentation chain that proves age and authenticity. Antique silver dealers price coin silver and sterling partly on the depth and consistency of the patina; a freshly polished 1830 coin silver spoon loses 40-60 percent of its auction estimate compared to the same piece with original cabinet patina intact. The same rule applies to US silver coinage. A circulated 1916-D Mercury dime cleaned to a bright shine grades AU-Details rather than VF-30 and loses thousands in value. Photograph the piece, document any maker stamps, and bring it to a specialist before doing anything else.