Sources & image credits
We follow a two-source rule: every factual claim should be supported by at least two independent trusted sources, or one authoritative primary source for official facts. Anything we cannot verify is marked, never asserted.
Primary & authoritative sources
- American Numismatic Association (ANA): Education authority: Fundamentals of Grading, correspondence courses, Official ANA Grading Standards, The Numismatist.
- American Numismatic Society (ANS): Scholarly research, collections, and publications (MANTIS database).
- ANACS: America's oldest grading service; strong on error/variety attribution.
- Bureau of Engraving and Printing (BEP): Currency production; engraving/printing context where relevant.
- CAC Grading (CACG / CAC): Grades coins and operates the CAC quality-within-grade sticker standard.
- Federal Reserve: Coin/currency circulation context.
- Independent Coin Graders (ICG): Grading and authentication service.
- Numismatic Guaranty Company (NGC): Authoritative for its own grading standards, NGC Coin Explorer, census, and modern coin grading guidance.
- Professional Coin Grading Service (PCGS): Authoritative for its own grading standards, PCGS Photograde, CoinFacts, and population data. Corroborate cross-service grading interpretations.
- Smithsonian National Numismatic Collection (NNC): The national coin collection of the United States, one of the largest in the world. High-quality reference photographs are released under Smithsonian Open Access (CC0 / public domain), free to use; we credit the Smithsonian as a courtesy. A preferred source for clean, single-side U.S. coin reference images.
- United States Mint: Primary authority for official specifications, designs, mintmarks, mintages, and the coin production process. Most U.S. Mint design images are works of the federal government; verify public-domain status case by case.
Reference books & publications
- ANA correspondence course materials: Grading and counterfeit-detection coursework. Concepts only.
- ANA Fundamentals of Grading (course concepts): Course concepts that inspired this project. Concepts only; do not reproduce course materials.
- Coin World: Long-standing trade publication; news, error/variety coverage, market context.
- Coin World's Making the Grade: Type-by-type key grading points for popular U.S. series. Research reference only.
- Grading Coins by Photographs: Photographic grading reference. Research reference only; do not reproduce its photographs.
- NGC Modern Coin Grading: Modern coin grading guidance. Research reference only.
- Numismatic News: Long-standing trade publication.
- PCGS Coin Grading and Counterfeit Detection: Grading and counterfeit-detection reference. Research reference only.
- The Official ANA Grading Standards for United States Coins: Standard reference for U.S. circulated and uncirculated grade descriptions. Research reference only; summarize and cite, never copy text.
Auction houses & specialist references
- GreatCollections: Auction examples/results; images with permission.
- Heritage Auctions: Documented sale results and high-quality example images. Images only with permission; corroborate general claims.
- Stack's Bowers Galleries: Auction examples/results; images with permission.
- VarietyVista: Die-variety attribution reference (RPMs, doubled dies). Useful for attribution leads; corroborate with a Tier-1/2 source before publishing claims.
Background sources
- CoinTalk Forum: Community leads only; trace any claim to a Tier 1-3 source before publishing.
- Wexler's Doubled Dies (doubleddie.com): Long-standing doubled-die reference site. Treat as corroboration/lead only; confirm the hubbing-process mechanics with U.S. Mint/PCGS before marking a claim verified.
- Wikipedia (numismatics articles): Overview + leads to cited sources only; never a sole source. Verify each image's specific license separately.
Image credits
We use only public-domain, compatibly licensed, our own, or permission-cleared images. Each image's license is recorded below.
| Image | Creator / source | License |
|---|---|---|
| 1884 Morgan Silver Dollar (Smithsonian NNC) | Daderot (photographer); National Museum of American History, Smithsonian | CC0 |
| 1878 Morgan Silver Dollar (Smithsonian NNC) | Daderot (photographer); National Museum of American History, Smithsonian | CC0 |
| 1889-P Morgan Dollar obverse (transparent cutout) | Design by George T. Morgan (U.S. Mint); scan/upload by Gore2000 | PD-USGov |
| Lincoln Cent obverse (U.S. Mint) | United States Mint (U.S. Department of the Treasury) | PD-USGov |
| 1909-S VDB Lincoln Wheat Cent reverse | Bruxton (photographer, own work) | CC0 |
| 1879-S Morgan dollar, graded NGC MS67+, obverse | Brandon Grossardt | CC BY-SA 3.0 |
| 1879-S Morgan dollar, graded NGC MS67+, reverse | Brandon Grossardt | CC BY-SA 3.0 |
| 1909-S VDB Lincoln Wheat cent, obverse | Lost Dutchman Rare Coins | CC BY-SA 3.0 |
| 1909-S VDB Lincoln Wheat cent, reverse | Lost Dutchman Rare Coins | CC BY-SA 3.0 |
| 1913 Type 1 Buffalo nickel, graded NGC MS65, obverse | Brandon Grossardt | CC BY-SA 3.0 |
| 1913 Type 1 Buffalo nickel, graded NGC MS65, reverse | Brandon Grossardt | CC BY-SA 3.0 |
| 1943-D Mercury dime, obverse | Brandon Grossardt | CC BY-SA 3.0 |
| 1943-D Mercury dime, reverse | Brandon Grossardt | CC BY-SA 3.0 |
| 1917 Type 1 Standing Liberty quarter, graded PCGS MS64 FH, obverse | Lance Keigwin | CC BY-SA 3.0 |
| 1917 Type 1 Standing Liberty quarter, graded PCGS MS64 FH, reverse | Lance Keigwin | CC BY-SA 3.0 |
| 1921 Peace dollar (high relief, first year), obverse | Remsty | CC BY-SA 4.0 |
| 1921 Peace dollar (high relief, first year), reverse | Remsty | CC BY-SA 4.0 |
| 1938 Jefferson nickel (Smithsonian NNC) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1996-S Roosevelt dime (obverse) | John R. Sinnock (coin); Heritage Auctions (image) | Public domain |
| 1996-S Roosevelt dime (reverse) | John R. Sinnock (coin); Heritage Auctions (image) | Public domain |
| 1932 Washington quarter (obverse) | John Flanagan (coin); Numismatic Guaranty Corporation (image) | Public domain |
| 1932 Washington quarter (reverse) | John Flanagan (coin); Numismatic Guaranty Corporation (image) | Public domain |
| 1945-D Walking Liberty half dollar (obverse) | Brandon Grossardt (photo); Adolph A. Weinman (coin design) | Public domain |
| 1950-D Franklin half dollar (Full Bell Lines) (obverse) | U.S. Mint (coin); Heritage Auctions (image) | Public domain |
| 1950-D Franklin half dollar (Full Bell Lines) (reverse) | U.S. Mint (coin); Heritage Auctions (image) | Public domain |
| Kennedy half dollar (U.S. Mint) (obverse) | United States Mint | Public domain |
| Kennedy half dollar (U.S. Mint) (reverse) | United States Mint | Public domain |
| 1892 Barber dime (Smithsonian NNC) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1913 Barber quarter (obverse) | Charles E. Barber (coin); U.S. Government work (image) | Public domain |
| 1913 Barber quarter (reverse) | Charles E. Barber (coin); U.S. Government work (image) | Public domain |
| 1899 Barber half dollar (obverse) | Charles E. Barber (coin); U.S. Government work (image) | Public domain |
| 1899 Barber half dollar (reverse) | Charles E. Barber (coin); U.S. Government work (image) | Public domain |
| 1858 Flying Eagle cent (Smithsonian NNC) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1860 Indian Head cent (Smithsonian NNC) (obverse) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1860 Indian Head cent (Smithsonian NNC) (reverse) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1866 Shield nickel, With Rays (Smithsonian NNC) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1887 Liberty Head V nickel, With CENTS (Smithsonian NNC) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1865 two-cent piece (obverse) | James B. Longacre (coin); Brandon Grossardt (photograph) | Public domain |
| 1865 two-cent piece (reverse) | James B. Longacre (coin); Brandon Grossardt (photograph) | Public domain |
| 1865 three-cent nickel (Smithsonian NNC) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1858 Seated Liberty half dime (Smithsonian NNC) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| 1876-CC twenty-cent piece (obverse) | William Barber (coin); Heritage Auctions (image) | Public domain |
| 1876-CC twenty-cent piece (reverse) | William Barber (coin); Heritage Auctions (image) | Public domain |
| 1877 Liberty Head double eagle (Smithsonian NNC) | U.S. Mint (coin); National Numismatic Collection, Smithsonian Institution (photograph by Jaclyn Nash) | Public domain |
| Flowing Hair Chain Cent, obverse | US Mint (coin), National Numismatic Collection (photograph by Jaclyn Nash) | Public domain |
| Flowing Hair Wreath Cent, obverse | US Mint (coin), National Numismatic Collection (photograph by Jaclyn Nash) | Public domain |
| Liberty Cap Large Cent, obverse | Coin: Joseph Wright, Image by Lost Dutchman Rare Coins | Public domain |
| Draped Bust Large Cent, obverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Classic Head Large Cent, obverse | Unknown authorUnknown author | Public domain |
| Coronet (Matron Head) Large Cent, obverse | Numismatic Guaranty Corporation | Public domain |
| Braided Hair Large Cent, obverse | Numismatic Guaranty Corporation | Public domain |
| Lincoln Memorial Cent, obverse | The Anthony Corp. | CC BY-SA 4.0 |
| Lincoln Bicentennial Cents, obverse | United States Mint | Public domain |
| Lincoln Shield Cent, obverse | United States Mint | Public domain |
| Three-Cent Silver (Trime), obverse | Unknown | Public domain |
| Flowing Hair Half Dime, obverse | Unknown authorUnknown author | Public domain |
| Draped Bust Half Dime, obverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Capped Bust Half Dime, obverse | Unknown authorUnknown author | Public domain |
| Draped Bust Dime, obverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Capped Bust Dime, obverse | Unknown authorUnknown author | Public domain |
| Seated Liberty Dime, obverse | US Mint (coin), National Numismatic Collection (photograph by Jaclyn Nash) | Public domain |
| Draped Bust Quarter, obverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Capped Bust Quarter, obverse | Unknown authorUnknown author | Public domain |
| Seated Liberty Quarter, obverse | Coin: Christian Gobrecht. Image by Lost Dutchman Rare Coins | Public domain |
| 50 State Quarters, obverse | Hoshie (talk) | Public domain |
| D.C. & U.S. Territories Quarters, obverse | Unknown | Public domain |
| America the Beautiful Quarters, obverse | John Flanagan | Public domain |
| American Women Quarters, obverse | Craig Campbell, Emily Damstra | Public domain |
| Flowing Hair Half Dollar, obverse | Unknown authorUnknown author | Public domain |
| Draped Bust Half Dollar, obverse | Unknown authorUnknown author | Public domain |
| Capped Bust Half Dollar, obverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Seated Liberty Half Dollar, obverse | Coin: Christian Gobrecht Image by Lost Dutchman Rare Coins | Public domain |
| Flowing Hair Dollar, obverse | United States Mint, Smithsonian Institution | Public domain |
| Draped Bust Dollar, obverse | Bobby131313 at English Wikipedia | Public domain |
| Gobrecht Dollar, obverse | Coin: Christian Gobrecht Image by Lost Dutchman Rare Coins | Public domain |
| Seated Liberty Dollar, obverse | Lost Dutchman Rare Coins for image, Christian Gobrecht for coin | Public domain |
| Trade Dollar, obverse | Coin: William Barber, Image by Lost Dutchman Rare Coins | Public domain |
| Eisenhower Dollar, obverse | Brandon Grossardt for the photograph; Frank Gasparro for the coin design. | Public domain |
| Susan B. Anthony Dollar, obverse | US Mint (coin); Heritage Auctions (image); modified by RHM22 | Public domain |
| Presidential Dollar, obverse | United States Mint | Public domain |
| American Innovation Dollar, obverse | Unknown author | Public domain |
| Gold Dollar, obverse | Professional Coin Grading Service | Public domain |
| Quarter Eagle ($2.50), obverse | Coin: John R. Sinnock, Image by Lost Dutchman Rare Coins | Public domain |
| Three-Dollar Gold, obverse | United States Mint | Public domain |
| Half Eagle ($5), obverse | Smithsonian National Numismatic Collection | Public domain |
| Eagle ($10), obverse | James St. John | Public domain |
| Classic Commemorative Gold, obverse | Unknown | Public domain |
| Modern Bullion Gold, obverse | United States Mint | Public domain |
| Flowing Hair Chain Cent, reverse | US Mint (coin), National Numismatic Collection (photograph by Jaclyn Nash) | Public domain |
| Flowing Hair Wreath Cent, reverse | US Mint (coin), National Numismatic Collection (photograph by Jaclyn Nash) | Public domain |
| Liberty Cap Large Cent, reverse | Coin: Joseph Wright, Image by Lost Dutchman Rare Coins | Public domain |
| Classic Head Large Cent, reverse | Unknown authorUnknown author | Public domain |
| Braided Hair Large Cent, reverse | Coin: Christian Gobrecht, Image by Lost Dutchman Rare Coins | Public domain |
| Three-Cent Silver (Trime), reverse | Unknown | Public domain |
| Flowing Hair Half Dime, reverse | Unknown authorUnknown author | Public domain |
| Draped Bust Half Dime, reverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Draped Bust Dime, reverse | US Mint (coin), National Numismatic Collection (photograph by Jaclyn Nash) | Public domain |
| Capped Bust Dime, reverse | Unknown authorUnknown author | Public domain |
| Seated Liberty Dime, reverse | US Mint (coin), National Numismatic Collection (photograph by Jaclyn Nash) | Public domain |
| 50 State Quarters, reverse | Unknown | Public domain |
| D.C. & U.S. Territories Quarters, reverse | United States Mint | Public domain |
| America the Beautiful Quarters, reverse | Works of the United States Government | Public domain |
| Flowing Hair Half Dollar, reverse | Unknown authorUnknown author | Public domain |
| Draped Bust Half Dollar, reverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Seated Liberty Half Dollar, reverse | Coin: Christian Gobrecht Image by Lost Dutchman Rare Coins | Public domain |
| Walking Liberty Half Dollar, reverse | Brandon Grossardt for the image; Adolph A. Weinman for the coin design. | Public domain |
| Flowing Hair Dollar, reverse | United States Mint, Smithsonian Institution | Public domain |
| Gobrecht Dollar, reverse | Marcomogollon | CC BY-SA 4.0 |
| Seated Liberty Dollar, reverse | Rosser1954 | CC BY-SA 4.0 |
| Trade Dollar, reverse | Unknown authorUnknown author | Public domain |
| Sacagawea / Native American Dollar, reverse | United States Mint | Public domain |
| American Innovation Dollar, reverse | Elana Hagler/United States Mint | Public domain |
| Quarter Eagle ($2.50), reverse | Unknown | Public domain |
| Three-Dollar Gold, reverse | United States Mint | Public domain |
| Half Eagle ($5), reverse | Smithsonian National Numismatic Collection | Public domain |
| Classic Commemorative Gold, reverse | Unknown | Public domain |
| Modern Bullion Gold, reverse | US Mint | Public domain |
| Draped Bust Large Cent, reverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Lincoln Shield Cent, reverse | MisfitMaid | CC BY-SA 4.0 |
| Capped Bust Half Dime, reverse | Unknown authorUnknown author | Public domain |
| Draped Bust Quarter, reverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Seated Liberty Quarter, reverse | Coin: Christian Gobrecht. Image by Lost Dutchman Rare Coins | Public domain |
| Capped Bust Half Dollar, reverse | Coin: Robert Scot, Image by Lost Dutchman Rare Coins | Public domain |
| Draped Bust Dollar, reverse | Bust_dollar_reverse.jpg: Bobby131313 at en.wikipedia derivative work: Br'er Rabbit | Public domain |
| Eisenhower Dollar, reverse | James St. John | CC BY 2.0 |
| Presidential Dollar, reverse | Rachel Bush | CC BY 2.0 |
| Gold Dollar, reverse | Unknown authorUnknown author | Public domain |
| Eagle ($10), reverse | James St. John | CC BY 2.0 |
| Lincoln Memorial Cent, reverse | Slashme | CC BY-SA 3.0 |