The Dime
10 cents
Today's dime is a three-layer sandwich: two outer layers of the same 75% copper, 25% nickel alloy used in the nickel, bonded to a core of pure copper. You can see the copper core as a thin stripe on the coin's edge. Before 1965, dimes were 90% silver. When the Coinage Act of 1965 removed silver, the clad design was recommended partly so the new dimes would work in vending machines alongside the older silver ones. Because a coin machine reads the skin and the copper core together, the balance between the two layers is what gives the dime its electromagnetic signature.
Composition & Tolerances
| Variant | Standard Clad Dime 1965–today | Historic Silver Dime 1873–1964 (2.50 g standard) | Counterfeit 1916-D Fakes Usually altered genuine dimes | Proposed 80/20 Clad Dime Mint recommendation, not law‡ |
|---|---|---|---|---|
| Copper | 91.67% | 10% | 10%§ | Core plus skin, % not set‡ |
| Nickel | 8.33% | — | — | Skin only, leaner than today‡ |
| Silver | — | 90% | 90%§ | — |
| Silver content | — | 0.0723 troy oz | 0.0723 troy oz (host coin) | — |
| Structure | Cupronickel skins over a copper core | Solid silver alloy | Solid silver (genuine host coin) | 80/20 cupronickel skins over a copper core |
| Target weight | 2.268 g | 2.500 g (38.58 grains) | 2.50 g (host coin)§ | Same as today‡ |
| Weight tolerance | Not published* | ±1.5 grains† (about ±0.097 g) | Host coin's spec§ | Not yet set |
| Composition tolerance | Not published | Not published | Host coin's spec§ | Not yet set |
| Diameter | 17.91 mm | 17.9 mm | 17.9 mm (host coin) | Same as today‡ |
| Thickness | 1.35 mm (strip ±0.038 mm*) | Not confirmed | Host coin's spec§ | Same as today‡ |
| Edge | Reeded, 118 reeds | Reeded | Reeded (host coin) | Same as today‡ |
| Magnetic? | No | No | No | No (copper-nickel skin) |
| Specific gravity | 8.92¶ | 10.34¶ | 10.34 (host coin)¶ | Same as today‡ |
| Conductivity | Skin 5.5%, core 100% (of copper) | Not published | Same as host coin | Matches today‡ |
| How to spot it | Copper stripe on the edge | Dated 1964 or earlier; no copper stripe | Compare the mint mark's shape and position with the four genuine positions | Not yet authorized |
Footnotes
Clad Dime: * The Mint sets its tolerance on clad strip thickness for dimes, quarters and half dollars (±0.0015 in, 0.038 mm); a finished-coin weight tolerance is not published. ¶ Specific gravity values are commonly cited collector figures. Conductivity is a percent of pure copper (IACS).
Silver Dime: † Historic legal tolerance, Newman Numismatic Portal. Earlier silver dimes: 2.70 g at 89.24% silver (1796–1837), 2.67 g at 90% (1837–53), 2.49 g at 90% (1853–73).
1916-D Fakes: § Most 1916-D fakes are genuine silver dimes with an added D mint mark or an altered date; the metal of struck counterfeits is not documented. NGC ranks the 1916-D as the second-most counterfeited U.S. coin.
80/20 Clad Dime: ‡ The Mint's seamless 80/20 option (2022 Biennial Report) needs approval from Congress. The Common Cents Act does not change the dime.
Sources
- U.S. Mint, Coin Specifications: https://usmint.gov/learn/coin-specifications
- Stack's Bowers, Liberty Seated Dime (1853 and 1873 weight changes): https://stacksbowers.com/coin-resource-center/us-coins/dimes/liberty-seated-dime/liberty-seated-dime-type-5-obverse-arrows-legend
- Newman Numismatic Portal, Tolerance: https://nnp.library.wustl.edu/concern/dictionaries/dict516903
- CoinWeek, Deceptive 1916-D Mercury Dimes: https://coinweek.com/deceptive-1916-d-mercury-dimes-fun-with-fakes/
- Numismatic News, Clad coins welcomed coolly by collectors: https://www.numismaticnews.net/archive/clad-coins-welcomed-coolly-by-collectors
- U.S. Mint 2022 Biennial Report to Congress: https://usmint.gov/wordpress/wp-content/uploads/2023/04/2022-USM-Biennial-Report_P5_FINAL.pdf
- CoinTalk, Coin Specific Gravity (collector chart): https://www.cointalk.com/goto/post?id=2132275
- Blue Sea Systems, Electrical Conductivity of Materials: https://www.bluesea.com/support/articles/Materials/108/Electrical_Conductivity_of_Materials
- USPTO, Coinage cladding alloy patent (C71300 conductivity): https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/10513768