1966 Dime Errors: Identification, SMS and Value Checks

Which 1966 dime features are errors, and what are they worth?

Which real coin details should I compare?

How do the normal features, errors and values differ?

Why is no mint mark normal on a 1966 dime?

John R. Sinnock’s Roosevelt design began in 1946. By 1966, ordinary dimes used copper-nickel-clad construction rather than the earlier silver alloy. The usual specification is 2.27 grams and 17.90 millimeters, with a reeded edge. The outer layers are 75% copper and 25% nickel over a copper core. A visible copper-colored edge is consistent with that normal construction.

Mint marks were omitted during 1965–1967. A 1966 dime without a letter is therefore not equivalent to the later 1982 No P dime or a No S Proof. First establish what should be present for the exact year and issue. The dime error guide by year separates those categories, while the Roosevelt dime value guide covers the wider series.

How do I check the 1966 SMS 5 on Cheek variety?

FS-401 is a recognized variety of the 1966 SMS dime. The name describes a small 5-shaped feature on Roosevelt’s cheek; it is not the date, a mint mark or a large numeral added to the design. Compare its exact position and shape with the attributed specimen. The arrow below locates the area, and the close-up shows the same coin at a useful scale.

What should the cheek detail look like?

The feature is small. Use diffuse light and compare the surrounding portrait detail as well as the mark itself. A scratch normally removes or displaces metal; a stain changes color. Neither becomes FS-401 because it resembles a digit in one photograph. An attributed holder and matching certificate are useful evidence, but still check that the actual coin agrees with them.

The pictured SP67 coin sold at Heritage on May 12, 2026. Its price applies to that attribution and preservation, not to every 1966 dime with a facial mark. Do not infer the variety’s manufacturing mechanism from the nickname alone.

What price evidence exists for 1966 dime errors?

These are selected historical transactions reviewed on November 12, 2026. They illustrate why attribution and grade must precede a value comparison. Heritage’s published realized total is not the seller’s net proceeds, and fees or taxes should not be added indiscriminately to a reported total. A guide value or seller’s asking price is a different kind of evidence.

How can damage imitate a dime error?

Grinding can thin a coin or remove an edge, chemicals can change color, and impact can flatten lettering or move metal. These effects happen after striking. A missing-clad-layer candidate needs more than a copper-colored face: compare weight and edge construction and have the surfaces examined. Do not chemically test, scratch or cut a collectible candidate.

A broadstrike and an off-center strike also need different evidence. A broadstrike can retain the full design on an expanded flan; an off-center strike loses part of the intended design. A photograph cropped too tightly cannot establish either. Use the grading guide to separate wear from a production fault before seeking an appraisal.

How can I check my coin in three steps?

1. 01Identify Roosevelt, the 1966 date and the reeded edge. Record both faces and the edge in neutral light. No mint mark and a copper-colored clad edge are normal starting observations.
2. 02For a suspected FS-401, compare the cheek with the attributed close-up and establish SMS status separately. For a planchet concern, measure weight and diameter; do not substitute a facial mark or surface color for physical evidence.
3. 03Look for displaced metal, filing, polishing, corrosion or altered surfaces. Keep a credible candidate uncleaned and obtain a specialist attribution before comparing transactions for the same variety, grade and finish.

What should I remember before pricing?

What else do collectors ask?

Which references support these checks?