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Last updated: August 13, 2026 · By White Metal Resources Editorial
Quick answer: Mexican silver marks combine a fineness number (925 sterling, 950 higher grade, or 900 older coin silver) with a national assay mark. From 1948 to about 1979 that assay mark was an eagle punch with a workshop number inside. From 1979 onward it is a spread-eagle plus a letter-and-number code that identifies the maker's shop and city.
Short on time? The essentials
- Mexico used two national silver assay systems in the twentieth century. The eagle-and-number system ran from 1948 to about 1979 and stamped a small eagle punch containing a maker's workshop number.
- The eagle system was replaced in 1979 to 1980 by a federal alphanumeric identification code. A late-model Mexican silver piece today may carry a code such as TS-01, where TS points to the city of Taxco and 01 to a specific registered workshop.
- The most common fineness stamped next to a Mexican assay mark is 925 for sterling silver, or 92.5 percent pure silver by weight. Sterling is the default for most twentieth century Taxco jewelry and hollowware.
- 950 silver at 95.0 percent pure is a higher grade common on hand-wrought Taxco workshop pieces, including work by William Spratling and his direct trainees. It sits between sterling and fine silver.
- Older Mexican silver carries a numeric 900 mark, or the phrase MEXICO SILVER, on pieces predating the 1948 eagle system. 900 is the same coin silver fineness used on nineteenth-century US coinage.
- The Taxco silver revival began when American designer William Spratling opened the Taller de Las Delicias in Taxco, Guerrero in 1931. Signed Spratling silver carries a strong collector premium above melt at well-attended auctions.
- Antonio Pineda (1919 to 2009), Hector Aguilar (1905 to 1986), and the Los Castillo workshop (founded 1939) each trained under or worked with Spratling. Their signed pieces also carry qualitative collector premiums.
- Melt value on a Mexican silver piece follows the same formula as any silver: fineness times gross gram weight, divided by 31.1035 grams per troy ounce, multiplied by the spot silver price per ounce.
- At an illustrative silver spot of 30 dollars per troy ounce, one gram of 925 silver holds about 89 cents of pure silver, one gram of 950 silver holds about 92 cents, and one gram of 900 silver holds about 87 cents.
- Silver held for retirement follows a separate 0.999 IRA fineness rule that no Mexican decorative silver on this page meets. Household Mexican silver is fine to own personally but cannot go inside a self-directed IRA account.
Mexican silver arrives in American households through many channels. It comes home from a Cabo cruise as a hand-wrought Taxco bracelet, or lands in a probate box as inherited flatware from a mid-century Spratling table service. It shows up in an estate sale lot as a numbered eagle punch on the back of a spoon. Or as a spread-eagle code on a pair of modern earrings bought last winter in Mexico City.
Each of those pieces carries a mark that reads in a fixed order once you know the two national systems Mexico has used. This page decodes the eagle-and-number system used from 1948 to about 1979 and the spread-eagle code system used since 1979. It also covers the three fineness standards of 925, 950 and 900 that sit next to those national marks. It closes with the melt math that runs on any Mexican silver piece.
The two eras of Mexican silver marking
Mexican silver of the twentieth century falls into two clear marking eras, plus a pre-1948 era with no consistent national mark. The first national assay system, introduced in 1948, stamped an eagle punch containing a workshop number. That system ran until it was officially abandoned by 1979 to 1980 and replaced by a federal alphanumeric identification code.
The Wikipedia article on the Mexican silver renaissance is direct on the transition. It states that Mexico introduced the national eagle-mark system in 1948 to indicate registered production and minimum silver standards, with each registered maker being assigned a number within the mark. The same article notes that the eagle mark was officially abandoned by 1979 to 1980 and replaced by a federal alphanumeric identification system.
Any Mexican silver piece with an eagle punch containing a workshop number therefore dates from a window that spans about three decades. Any piece with a spread-eagle plus alphanumeric code dates from the late 1970s or later. A piece with only a maker's name or the phrase MEXICO SILVER predates the eagle system and is dated by style and by maker research.
Fineness marks work the same way across both eras. The number stamped next to the national assay mark is the millesimal silver content of the alloy. 925 for sterling, 950 for higher grade Taxco work, and 900 for older coin silver are the three standards a general reader will meet on inherited Mexican silver.
The eagle assay system, 1948 to 1979
From 1948 to about 1979, Mexican silver carried an eagle assay mark stamped near the maker's name. The eagle punch contained a workshop number that identified a specific registered producer. Eagle 3, for example, was assigned to the Los Castillo workshop of Taxco. Eagle 1 was assigned to William Spratling's Taller de Las Delicias in Taxco.
Numbers within the eagle mark climbed as new workshops registered with the Mexican assay authority. Numbered eagle punches ran into the double digits and beyond, with active shops in Taxco, Mexico City, and other silversmithing centers each drawing a unique number. A collector or dealer with a workshop number reference can look up a numbered eagle mark and match it to a specific taller and its production window.
The eagle mark travels with a fineness stamp on the same piece. That fineness is usually 925 for sterling silver or 950 for a higher grade alloy. The mark cluster also includes the maker's own stamp, which may be a name, a monogram, or a workshop logo. All four elements of the classic Mexican silver mark cluster appear together on a well-marked piece from the eagle era.
Certain numbered eagle marks are of high interest to collectors. Eagle 1 for Spratling is the most sought after, since it appears on pieces from the Taxco silver revival's origin workshop. Eagle 3 for Los Castillo, Eagle 9 for Hector Aguilar's Taller Borda, and Eagle 17 for Antonio Pineda are also frequently cited in auction catalogues and dealer references. Each numbered eagle carries the qualitative auction premium of its associated shop.
The spread-eagle code system, 1979 to today
The eagle-and-number system was officially abandoned by 1979 to 1980 and replaced by a federal alphanumeric identification system. A Mexican silver piece made under the current system carries a spread-eagle profile stamp plus a letter-and-number code. Examples include TS-01 for Taxco shop 01, or TA-15 for another Taxco maker.
The letter portion of the code identifies the city or region of production, and the number identifies the specific registered workshop within that city. TS and TA both point to Taxco, MX to Mexico City, and additional letter codes identify smaller silversmithing centers. The Mexican Direccion General de Normas administers the current registration system through federal standards for silver goods manufactured in Mexico.
Fineness marks under the current system read the same as under the eagle system. A modern Mexican silver piece marked 925 is sterling silver at 92.5 percent pure by weight. A modern piece marked 950 is higher grade silver at 95.0 percent pure. The current system also allows fine silver bullion products at 999 for buyers who want investment grade metal outside the decorative market.
Modern Mexican silver from a legitimate registered workshop is a well-marked and well-regulated product. It carries a national spread-eagle stamp, a fineness number, and a maker code that ties the piece back to a specific taller in a specific Mexican city. Any piece stamped with the phrase MEXICO or Mexican Silver but missing the spread-eagle plus alphanumeric code should be checked carefully, since unmarked tourist ware and outright counterfeits do circulate in the American import market.
925 sterling on Mexican silver
A 925 mark on Mexican silver denotes sterling silver at 925 parts per thousand fineness, or 92.5 percent pure silver by weight. Sterling silver is the world's most common decorative silver standard, used on British, American, Mexican and modern Continental silver. The other 7.5 percent of the alloy is copper, added for hardness.
Sterling is the default fineness on twentieth century Taxco silver, whether the piece dates from the eagle era or the current spread-eagle era. A large share of Mexican silver jewelry sold in the American import market since 1948 is stamped 925 alongside a maker's mark and a national assay mark. A modern silver ring or bracelet bought at a Mexican silver shop today is almost always sterling.
Mexican sterling matches the fineness of American sterling flatware, English sterling hollowware, and modern European sterling jewelry. A 925 Mexican silver bracelet holds the same 92.5 percent silver content per gram of alloy as a piece of sterling from Gorham, Tiffany or Reed and Barton. The melt math is therefore identical across all sterling silver, regardless of country of origin.
Mexican sterling from named makers carries a qualitative auction premium above simple sterling melt. A Spratling sterling bracelet, an Aguilar Taller Borda sterling ring, or a Pineda sterling brooch commonly sells well above melt at a well-attended auction, driven by the maker's design language and the piece's provenance. This page does not quote dollar figures on those premiums, since they depend on completed public auction sales for the specific piece.
950 higher grade Taxco silver
A 950 mark on Mexican silver denotes silver at 950 parts per thousand fineness, or 95.0 percent pure silver by weight. 950 sits above sterling at 925 and below fine silver at 999. It is a higher grade silver alloy used on hand-wrought Taxco workshop pieces, including work by William Spratling and by many of his direct trainees.
Spratling's Taller de Las Delicias worked at the 950 standard for a large share of its handwrought output. That higher fineness gave his silver a softer working characteristic and a slightly whiter finish than sterling at 925. The 950 mark on a Spratling piece is a routine feature of his production, alongside his personal script or block signature and the eagle 1 workshop mark of his taller.
950 silver is also a familiar mark on the higher grade output of other Taxco workshops. A Los Castillo hollowware piece, an Aguilar Taller Borda decorative bowl, or a Pineda modernist brooch may carry 950 in place of 925 when the workshop chose the higher fineness for that specific piece. The mark cluster otherwise reads the same, with a numbered eagle from the pre-1980 era or a spread-eagle plus code from the current system.
950 is the same numeric fineness as the French 1st standard silver marked with a Minerva head. It is also the numeric fineness of modern silver American Platinum Eagle proof coin frames and of some Latin American commemorative issues. The 950 alloy is not unique to Mexico, but its association with the Taxco school of silver design makes it a strong identification marker on estate silver from that source.
900 older Mexican coin silver
A 900 mark on Mexican silver denotes silver at 900 parts per thousand fineness, or 90.0 percent pure silver by weight. 900 is the same coin silver fineness used on nineteenth-century United States circulating silver coinage. On Mexican silver, the 900 mark appears mainly on older pieces that predate the 1948 eagle system and on some transitional pieces from the earliest years after 1948.
Older Mexican decorative silver may also carry the phrase MEXICO SILVER stamped on the base or the handle. That phrase functions as a country of origin plus a plain-English silver purity claim, without a numeric fineness. Pieces marked only MEXICO SILVER usually test in the 900 range on hand assay, though variation exists across pre-1948 workshops.
Pre-1948 Mexican silver is dated by style and by maker research rather than by any national assay stamp. William Spratling's earliest Taller de Las Delicias production from the 1930s falls into this window, and those pieces are among the most sought after Spratling silver by advanced collectors. Signed pre-1948 Spratling silver commonly sells at a strong premium over melt at specialist auctions.
Coin silver at 900 fineness also appears on Mexican silver peso coins and on other silver Mexican circulating coinage from the nineteenth and early twentieth centuries. Those coins fall outside the decorative silver market and into the numismatic market, where their value depends on date, mint mark, condition and rarity rather than on melt content alone. Numismatic valuation of Mexican coins is outside the scope of this page.
Named makers whose signed silver carries a premium
Signed Mexican silver from a small group of twentieth century workshops carries a qualitative auction premium above the melt content of the piece. This section identifies four of the most cited makers on the Taxco school of silver design and provides basic biographical anchors for each. Auction premiums are qualitative here and vary with specific pattern, condition and provenance.
William Spratling (22 September 1900 to 7 August 1967) was an American architect, writer, artist and silver designer who established the Taller de Las Delicias in Taxco, Guerrero in 1931. Through his workshop, Spratling organized modern Taxco silver production and trained the generation of Mexican silversmiths who founded most of the other named workshops. Signed Spratling silver is the highest-premium category of Mexican silver at auction.
Antonio Pineda Gomez (19 July 1919 to 14 December 2009) was a Mexican silversmith and designer from Taxco. He briefly apprenticed at Spratling's workshop as a child and later worked in Spratling's sales and management. He opened his own taller in Taxco in 1939. Pineda's modernist silver jewelry and hollowware built on abstracted pre-Columbian forms and Art Deco geometry. A Fowler Museum retrospective in 2008 to 2009 catalogued his hallmark chronology.
Hector Aguilar (1905 to 1986) was a Mexican silversmith and jewelry designer who worked at Spratling's Las Delicias as shop manager and then apprentice before founding his own Taller Borda in Taxco in 1939. Taller Borda grew to more than 300 artisans during the Second World War and supplied jewelry and metalwork to retailers in Mexico and the United States. Signed Aguilar or Taller Borda silver is a mid to high tier premium category at auction.
Los Castillo was a Mexican silver, jewelry and decorative-arts workshop founded in 1939 in Taxco by silversmith Antonio Castillo with his three brothers, his wife Margot van Voorhies Carr and his first cousin Salvador Teran. The Castillo brothers had trained at Spratling's Taller de Las Delicias. Los Castillo employed more than 300 workers at its wartime peak, ran on a reduced basis for decades, and closed in 1995. Signed Los Castillo pieces carry a solid collector premium at auction.
Melt content per gross gram across the three fineness standards
The table below runs the melt content per gross gram of alloy across the three Mexican silver fineness standards. All figures use an illustrative silver spot price of 30 dollars per troy ounce, which is a stated example and not a market quote. The formula is fineness times gross gram weight divided by 31.1035 grams per troy ounce, multiplied by the spot price per ounce.
| Mark | Fineness | Pure silver per gram of alloy | Troy ounces of silver per gram of alloy | Melt value per gram at 30 dollars per ounce |
|---|---|---|---|---|
| 900 | 0.900 | 0.900 grams | 0.02893 ozt | 0.8681 dollars |
| 925 | 0.925 | 0.925 grams | 0.02974 ozt | 0.8922 dollars |
| 950 | 0.950 | 0.950 grams | 0.03054 ozt | 0.9163 dollars |
Computed from the standard melt formula: fineness times gross grams divided by 31.1035 grams per troy ounce, multiplied by the stated spot price. Fineness values from Wikipedia Fineness article (checked August 2026). Spot price of 30 dollars per troy ounce is an illustrative example, not a current market quote.
The gap between 900 and 950 silver comes out to about 4.8 cents per gross gram at an illustrative 30 dollars per ounce spot price. On a 400 gram Mexican silver hollowware piece, that is a 19 dollar difference in melt content between the 900 and 950 alloy. Fineness reads directly off the numeric stamp, and each of the three Mexican standards prices at a slightly different rate per gram of alloy.
Mexican silver standards on the fineness scale
The chart below places the three Mexican silver standards on one millesimal fineness scale alongside continental 800 silver and fine silver bullion at 999 for reference. The visual makes clear that the Mexican trio of 900, 925 and 950 all sit in the higher end of the decorative silver range, well above the continental 800 floor.
Two takeaways sit in the chart. First, all three Mexican decorative silver standards sit well above the continental 800 European floor, so a Mexican silver piece typically holds more pure silver per gram than an inherited German or Danish piece. Second, the three Mexican standards span a narrow 50 parts per thousand band, so identification errors between 900, 925 and 950 cost real melt dollars only on heavier hollowware.
A six step method for decoding a Mexican silver mark
The steps below turn the country notes above into one repeatable method. Follow the six steps on any Mexican silver piece to identify the fineness, the era, the workshop, and the melt math in a fixed order.
- Locate every stamp on the piece. Marks on Mexican silver jewelry sit on the inside of a band or the back of a pendant. Marks on flatware sit on the back of the handle near the join. Marks on hollowware sit under the foot or inside the lid rim. Photograph the marks under raking light so every stamp is visible.
- Read the numeric fineness first. A three-digit number of 900, 925 or 950 is the millesimal silver content. That number sets the melt math for the piece, without any other information from the mark cluster.
- Read the national assay mark next. A small eagle punch containing a workshop number means Mexican silver from 1948 to about 1979. A spread-eagle profile plus a letter-and-number code means Mexican silver from 1979 or later. Only a maker's name plus MEXICO SILVER or 900 means a pre-1948 piece dated by style.
- Match the workshop number or code to a known maker. Cross-check a numbered eagle against a workshop reference. Cross-check a letter-and-number code against the current Mexican assay registry city codes such as TS for Taxco.
- Read the maker's own stamp. Mexican silver often carries the maker's name in a rectangle or an initials monogram in a shield. A script Spratling signature, a Los Castillo family stamp, a Taller Borda maker mark, or an Antonio Pineda block signature each identify a specific taller.
- Run the melt math. Weigh the piece on a kitchen or jewelry scale in grams. Multiply the gross gram weight by the fineness as a decimal. Divide by 31.1035 to get troy ounces of pure silver. Multiply by the spot silver price to get melt value in dollars.
Any Mexican silver piece that fails at step 2 should be checked for a mark in a less obvious spot before being treated as unmarked. Any piece that fails at step 3 may still be Mexican silver of a valid standard, but it is harder to attribute to an era and often prices at a discount for that reason. Steps 4 through 6 apply to every piece with a legible fineness.
A worked melt example on a 925 sterling Taxco piece
Reading the mark decides the fineness. The fineness then runs the melt math on any weight and any stated spot price. The example below applies the six step method to a Taxco 925 sterling bracelet from the eagle era and converts the fineness numeral into an illustrative melt value.
The same six step method reads a 950 higher grade Spratling piece, a 900 older coin silver Mexican piece, or a modern spread-eagle marked ring. The melt math changes only in step 6, where the fineness multiplier is 0.900, 0.925 or 0.950 depending on the numeric stamp on the piece.
Limits and caveats to keep in mind
Every fineness number on this page is a legal or trade standard tied to a national marking system. It asserts the standard a piece was made to, not a live assay of the object in hand. A worn, repaired or altered piece can test slightly under the marked standard. Specialist verification via X-ray fluorescence is the only way to check the actual silver content on a specific piece.
All melt figures on this page are computed from a stated silver spot price. Silver spot moves continuously during market hours. The 30 dollars per troy ounce spot used in the table and example is an illustrative round number for computation. It is not a forecast, not a current market quote, and not a guarantee of any future price.
Numbered eagle marks and spread-eagle codes rely on workshop reference tables for full identification. Well-known numbers such as eagle 1 for Spratling, eagle 3 for Los Castillo, eagle 9 for Aguilar and eagle 17 for Pineda are widely cited in dealer and auction sources. Less common numbered eagles require specialist reference works to attribute to a specific taller with confidence.
Collector premiums for named makers are qualitative and vary with the auction market. A signed Spratling sterling bracelet in original condition commonly sells at a strong premium over melt at a specialist auction, driven by the maker's mark and pattern. This page does not quote dollar figures on maker premiums, because those depend on completed public auction sales for the specific piece.
Rare-coin numismatic value is outside the scope of this page. A pre-1948 Mexican silver peso, an older Mexican silver commemorative issue, or a scarce mint mark on a nineteenth-century Mexican silver coin can carry a numismatic premium far above its 900 silver melt content. That valuation belongs to specialist coin dealers rather than to a decorative silver melt reference.
Silver held for retirement follows a separate fineness rule at 0.999 or higher. The Internal Revenue Code sets the minimum for silver held in a self-directed IRA at 0.999 fineness. That threshold sits well above every Mexican decorative silver standard on this page, a topic covered in our silver IRA fineness explainer. Mexican silver at 900, 925 or 950 is fine to own personally without restriction, but cannot go inside a self-directed IRA account.
Mexican silver mark questions, answered
What does a 925 mark on Mexican silver mean?
A 925 mark means the piece is sterling silver at 925 parts per thousand fineness, or 92.5 percent pure silver by weight. Sterling is the default fineness on twentieth century Taxco silver and on most modern Mexican silver jewelry. The other 7.5 percent of the alloy is copper, added for hardness.
What does a 950 mark on Mexican silver mean?
A 950 mark means the piece is silver at 950 parts per thousand fineness, or 95.0 percent pure silver by weight. 950 sits above sterling at 925 and below fine silver at 999. It is a higher grade alloy common on hand-wrought Taxco workshop pieces, including work by William Spratling and by many of his direct trainees.
What is the eagle number inside the small punch on my Mexican silver?
The eagle mark is the Mexican national silver assay mark used from 1948 to about 1979. The number inside the eagle identifies a specific registered workshop. Eagle 1 was assigned to William Spratling's Taller de Las Delicias, eagle 3 to Los Castillo, eagle 9 to Hector Aguilar's Taller Borda, and eagle 17 to Antonio Pineda. Higher numbers correspond to later or smaller registered talleres.
What does a spread-eagle plus letter-and-number code mean?
The spread-eagle profile plus a letter-and-number code is the current Mexican silver national mark, in use since the eagle-and-number system was abandoned by 1979 to 1980. The letters identify the city of production (TS for Taxco, MX for Mexico City), and the number identifies the specific registered workshop within that city.
Is silver marked MEXICO SILVER without a number real silver?
Usually yes, but it predates the 1948 eagle assay system and is dated by style. Pre-1948 Mexican decorative silver commonly tests around the 900 coin silver level on hand assay. Pieces marked only MEXICO SILVER or MEXICO 900 with a maker's name are consistent with genuine older Mexican silver, though X-ray fluorescence is the only way to confirm the actual fineness on a specific piece.
How do I compute melt value on a Mexican silver piece?
Weigh the piece on a kitchen or jewelry scale in grams. Multiply the gross gram weight by the fineness as a decimal, so 0.925 for sterling or 0.950 for higher grade. Divide the result by 31.1035 grams per troy ounce to get pure silver in troy ounces. Multiply by the current spot silver price per ounce for the melt value in dollars.
Do signed Taxco pieces sell above melt value?
Yes, and the premium can be significant on the most sought-after makers. Signed Spratling silver, Los Castillo hollowware, Aguilar Taller Borda jewelry and Antonio Pineda modernist pieces all carry qualitative premiums above melt at well-attended auctions. Actual premiums vary with pattern, condition, provenance and buyer competition, and require specialist auction records for accurate pricing.
Can Mexican silver at 925 or 950 go inside a self-directed IRA?
No. The Internal Revenue Code sets the fineness minimum for silver held in a self-directed IRA at 0.999. Every Mexican decorative silver standard on this page sits below that line, so hallmarked Taxco jewelry, hollowware and flatware cannot be held inside a self-directed IRA account. Mexican silver at 900, 925 or 950 can be held personally without any IRA-related restriction.
Sources
- Wikipedia, Mexican silver renaissance (national eagle-mark assay system introduced in 1948 to indicate registered production and minimum silver standards; each registered maker assigned a number within the mark; system officially abandoned by 1979 to 1980 and replaced by a federal alphanumeric identification system; Taxco silver revival led by William Spratling from the 1920s; more than 150 silver shops operating in Taxco by the early 1950s; principal figures including Frederick W. Davis, Hector Aguilar, Antonio Pineda, Margot van Voorhies Carr and Los Castillo). Checked August 2026.
- Wikipedia, William Spratling (American architect, writer, artist and silver designer, 22 September 1900 to 7 August 1967; established the Taller de Las Delicias in Taxco, Guerrero in 1931; trained generations of Mexican silversmiths; workshop became institutional origin of the Taxco school of silver design; trainees included Antonio Pineda, Hector Aguilar, Antonio Castillo, Jorge Castillo, Salvador Teran and Reveriano Castillo; died in an automobile accident near Taxco in 1967). Checked August 2026.
- Wikipedia, Antonio Pineda (silversmith) (Antonio Pineda Gomez, 19 July 1919 to 14 December 2009; Mexican silversmith and designer; brief childhood apprenticeship at Spratling's workshop; established own taller in Taxco in 1939; workshop grew from about 10 smiths to about 100; 2008 to 2009 Fowler Museum retrospective Silver Seduction: The Art of Mexican Modernist Antonio Pineda documented his hallmark chronology; won the first Galardon Nacional at the National Silver Fair in 1953). Checked August 2026.
- Wikipedia, Hector Aguilar (silversmith) (Mexican silversmith and jewelry designer, 1905 to 1986; associated with the twentieth-century silver renaissance in Taxco and Mexican modernism; worked for William Spratling at the Taller de Las Delicias; founded Taller Borda in Taxco in 1939; Taller Borda expanded to more than 300 artisans during the Second World War, supplied jewelry to retailers in Mexico and the United States, and produced identification bracelets and chains for American military personnel). Checked August 2026.
- Wikipedia, Los Castillo (Mexican silver, jewelry and decorative-arts workshop founded in 1939 in Taxco, Guerrero by silversmith Antonio Castillo with his three brothers Jorge Chato Castillo, Miguel Castillo and Justo Coco Castillo, his wife Margot van Voorhies Carr and his first cousin Salvador Teran; Castillo brothers trained at William Spratling's Taller de Las Delicias; more than 300 workers at wartime peak; closed in 1995). Checked August 2026.
- Wikipedia, Fineness (millesimal fineness definitions and world silver standards; sterling silver at 925 parts per thousand; 950 as a higher grade silver alloy also used for French 1st standard silver; 900 as the coin silver standard used on nineteenth century United States circulating silver coinage; 999 as fine silver bullion; alloy compositions typically silver with copper for hardness). Checked August 2026.
- Wikipedia, Silver hallmarks (national silver marking systems by country; sterling standard at 925 marked STERLING or 925 or 925/1000; French 1st standard at 950 marked with the Minerva head; role of national assay marks alongside numeric fineness stamps and maker's marks). Checked August 2026.
- Wikipedia, Taxco (Taxco de Alarcon, city in the state of Guerrero, Mexico; silversmithing reinvigorated in Taxco by American William Spratling from the 1920s; first workshop set up on Calle de Las Delicias in Taxco; today more than 3,000 silversmith artisans call Taxco home; William Spratling Museum contains silver and archaeological pieces from Spratling's personal collection). Checked August 2026.
- Electronic Code of Federal Regulations, Federal Trade Commission Guides for the Jewelry, Precious Metals, and Pewter Industries (16 CFR Part 23, legal requirements for representing an object as silver, sterling silver, or coin silver in the United States, including quality-mark rules for imported silver goods). Checked August 2026.
- Cornell Legal Information Institute, 26 U.S.C. section 408 (silver fineness rule for IRA metals at 0.999 minimum, referenced to the delivery standard of a regulated futures contract; excludes decorative Mexican silver at 900, 925 or 950 from self-directed IRA accounts). Checked August 2026.
