Mercury Dime Errors & Varieties Guide (1916–1945)

Mercury Dime Errors & Varieties Guide

The Mercury dime (Winged Liberty Head dime, 1916–1945) is one of the most productive series in American numismatics for error and variety collectors. Adolph Weinman's intricate design demanded high striking pressure, and the operational chaos of two World Wars created the conditions for landmark errors — most famously the 1942/1 overdate, universally regarded as the 'King' of the series, and the 1945-S Micro S, a product of wartime mintmark punch recycling. The consistent 90% silver composition across the entire run means there are no transitional planchet errors, but the hand-punched mintmark process generated Repunched Mintmarks (RPMs) throughout, and the silver alloy's metallurgical vulnerabilities produced lamination defects across all dates. This guide covers every documented Trophy and Findable error in the series with diagnostics, values, and authentication protocols. For year-by-year values of standard (non-error) Mercury dimes, see our complete Mercury Dime value guide.

Mercury Dime Error Values & Price Guide

Mercury Dime Error Value Chart

Every cataloged Mercury dime error and variety with typical market values reflecting the 2020–2024 auction period. Trophy-tier errors are highlighted. Click the error name to jump to the detailed identification section; click the year/mint cell (where linked) for the full year-specific error guide.

Values represent typical market prices reflecting the 2020–2024 auction market, updated to early 2025. Actual prices depend on individual coin quality, Full Bands (FB) designation, eye appeal, and market conditions. All Mercury dimes contain 90% silver (0.0723 troy oz) and carry a melt value floor that fluctuates with the silver spot price. For standard Mercury dime values by date and mint, see our complete Mercury Dime value guide.

How to Identify Mercury Dime Errors

Required Tools

• 10× loupe — mandatory for all die variety attribution (overdates, RPMs, DDO, mintmark varieties)
• Directional LED or fiber-optic light source — held at an oblique angle, directional light reveals mintmark doubling, die polish lines, and raised overdate elements that flat lighting obscures
• Precision scale (0.01g resolution) — useful for verifying a coin's weight against the standard 2.50g specification; significant deviation may indicate a planchet issue

Hub Doubling (left) vs Machine Doubling (right): genuine hub doubling adds to letter width with fully raised, rounded secondary images; machine doubling creates flat, shelf-like steps that reduce letter size and have zero numismatic value

Step-by-Step Inspection Workflow

1. Identify the year and mintmark first. The year is on the obverse (front). The mintmark — D (Denver) or S (San Francisco) — is on the reverse, to the LEFT of the fasces bundle near the bottom rim. No letter means Philadelphia Mint.
2. Flag key-variety years immediately. If the coin reads 1942 (P or D), 1945-S, 1939-P, or 1928-S, set it aside for dedicated examination before anything else.
3. On any 1942-P or 1942-D: examine the date under 10× magnification. Focus on the final digit '2.' A flat, raised bar protruding from the LEFT side of the '2' is the '1' from the 1941 hub — the 1942/1 overdate. Also check the '4' for a notch at the bottom of its upright and a secondary serif at the top. In worn coins (VG–Fine), the notched '4' may be the key pickup point when the '2/1' detail is smoothed. See 1942/1 Overdate section.
4. On any 1945-S: compare the mintmark size to a reference. The Micro S (FS-501) is noticeably shorter and more compact than the standard S. The difference is visible even without a side-by-side reference once you know what to look for — the Micro S looks sharp, deep, and small; a polished-down standard S looks wispy and faint. Also check the serif orientation for the Inverted S (FS-504). See 1945-S Micro S section.
5. On any 1939-P: check IN GOD WE TRUST for doubling. The 1939 DDO (FS-101) shows Class V pivoted hub doubling strongest on the word 'TRUST.' Key distinction: genuine hub doubling has FULL RELIEF secondary images that add to letter width; machine doubling is flat, shelf-like, and makes letters appear thinner. See 1939 DDO section.
6. On any 1940-S or 1941-S: inspect the mintmark for repunching. Under 10× magnification, look for a secondary 'S' outline positioned to the north or west of the primary punch, or doubled serif tips.
7. On any coin: check the rim and edge for clip errors. A crescent-shaped void at the rim is a clipped planchet candidate — but authentic only if the rim 180° opposite the void is also weak or missing (the Blakesley Effect).
8. On any coin: scan surfaces for lamination peels. Look for areas where the surface appears to be separating in layers or where a thin flap of metal is lifting away.

Mercury Dime Composition & Weight Reference

Most Valuable Mercury Dime Errors

1942/1 Mercury Dime Overdate — Philadelphia (FS-101)

The 1942/1 Philadelphia overdate is universally regarded as the 'King' of the Mercury dime series. It is a Class III (Design Hub) Doubling — a catastrophic production error where a working die received its first impression from a 1941-dated hub, was annealed (softened) for re-hardening, and then struck a second time with a 1942-dated hub. The two date impressions physically overlap on the die face. The '1' from 1941 and the '2' from 1942 are both fully raised design elements, visible to the naked eye in grades VF and higher.

1942/1 Philadelphia overdate close-up: flat raised bar of the '1' protruding from the left of the '2,' notch at the bottom of the '4' upright, and secondary serif at the top of the '4'

Pickup Points

1. The '1' bar: The most obvious feature. A sharp, flat raised bar — the remnant of the 1941 '1' — protrudes clearly from the LEFT side of the final '2' in the date. This is not a ghost or a smear; it is a fully formed raised element with smooth metal flow surrounding it. In grades VF and higher, this is visible to the naked eye.
2. The notched '4': A secondary but critical diagnostic, especially useful in lower grades (VG–Fine) where the '2/1' detail may be worn smooth. There is a distinct notch at the bottom of the upright of the '4' and a secondary serif at the top.
3. Die polish line: A diagonal die polish line is often visible extending from the crossbar of the '4' toward the rim. On the reverse, a thin polish line may run from the base of the fasces to the olive branch stem. These markers confirm the specific die pair (Die 1).

Full obverse of 1942/1 Philadelphia Mercury dime — arrow marks the date field at lower right where the overdate is located

Values

• AU50: ~$1,200
• MS65: ~$9,600–$12,000
• MS66FB: ~$45,900+ — auction record (PCGS Auction Prices — 1942/1 MS)

Full population data and price history: PCGS CoinFacts for the 1942/1 Philadelphia. Market price tracking across platforms: PriceCharting — 1942/1 Mercury Dime.

For the complete 1942 Mercury dime error guide, see 1942 Mercury Dime Errors.

1942/1-D Mercury Dime Overdate — Denver (FS-101)

The 1942/1-D shares the same origin as the Philadelphia overdate: a die received a first impression from a 1941 hub and a second from a 1942 hub. That die was then shipped from the Philadelphia Mint (where all working dies for all mints were manufactured) to the Denver Mint for use. The Denver variety is subtler and harder to detect than its Philadelphia counterpart — the '1' spread is tighter, requiring 5×–10× magnification to confirm. It is considered rarer in high grades.

1942/1-D Denver overdate: subtle spur of the '1' visible beneath the base of the '2' — less dramatic than the Philadelphia version and requiring 5×–10× magnification to confirm

Pickup Points

1. The '1' spur: Less dramatic than the Philadelphia variety. The '1' appears as a spur or line visible beneath and to the left of the base of the '2.' The spread is tighter than the Philadelphia example. Requires 5×–10× magnification.
2. 'R' in LIBERTY: A subtle but advanced diagnostic. The right leg of the 'R' in LIBERTY may appear shortened — a characteristic of the 1942 hub modification — with possible traces of the 1941 full leg creating a hybrid appearance.
3. Die gouge near mintmark: Some die states show a small die gouge or 'dot' near the 'D' mintmark on the reverse. This marker is used to confirm the specific Denver die pair.
4. AW Monogram: The Adolph Weinman monogram to the right of Liberty's neck may show slight doubling or weakness compared to a standard die, attributable to the different hubbing pressures in the overdate creation.
5. Mintmark verification: The 'D' must match known 1942-D punch style and position. The primary counterfeit is a genuine 1942/1 Philadelphia coin with a soldered 'D' added. On a genuine Denver coin, the obverse die polish lines match the Denver die pair — which differs from the Philadelphia die pair.

Values

• AU50: ~$1,000–$1,200
• MS65: ~$9,000–$12,000
• MS66FB: ~$40,800 — see PCGS CoinFacts — 1942/1-D FS-101 FB

For the complete 1942 Mercury dime error guide, see 1942 Mercury Dime Errors.

1939 Mercury Dime Doubled Die Obverse (FS-101)

The 1939 DDO (FS-101) is the most distinct doubled die of the middle years of the Mercury dime series. It is caused by Class V (Pivoted Hub) Doubling, where the die rotated at a pivot point near the rim between hubbings. The rotation creates doubling that increases toward the center of the coin and diminishes near the rim at the pivot point. The strongest doubling is found on the motto 'IN GOD WE TRUST.'

1939 DDO FS-101: doubled letters in 'TRUST' with full-relief secondary images that add to letter width and show distinct separation and corner notching — characteristic of Class V pivoted hub doubling

Pickup Points

1. 'TRUST' separation: The letters in 'TRUST' show the strongest doubling. There is distinct separation and notching at the corners of each letter. The doubling spreads toward the center of the coin — characteristic of Class V pivot doubling.
2. Date doubling: The date also shows a secondary image slightly offset from the primary digits.
3. Full relief test: ALL doubled elements on a genuine DDO have full relief and rounded contours that ADD to letter width. They match the surface curvature of the main device. This is the definitive distinction from machine doubling.

Values

• MS65: ~$500
• MS67: ~$500–$800 — see GreatCollections 1939 DDO MS-67 example
• MS68:$12,650 — auction record (PCGS Auction Prices — 1939 DDO FS-101)

The 1939 DDO applies exclusively to Philadelphia mint coins (no mintmark). Denver and San Francisco 1939 dimes do not carry this variety.

1945-S Micro S Mercury Dime (FS-501)

The 1945-S Micro S is a direct product of wartime resource constraints at the San Francisco Mint. Suffering from equipment shortages, the Mint used a mintmark punch originally intended for Philippine centavo coinage struck in San Francisco — a punch significantly smaller than the standard dime punch. The result is a distinctly compact 'S' that is noticeable to the naked eye when compared to the standard 1945-S. PCGS estimates approximately 30,000 survivors across all grades, so the coin is not exceedingly rare in circulated grades. The premium comes at the intersection of high grade AND Full Bands, because 1945-S striking pressure was generally weak, making a Micro S with Full Bands an extreme condition rarity.

1945-S Micro S (left) vs Standard 'Trumpet Tail' S (right): Micro S is visibly shorter with sharp, boxed loop shapes; Standard S is taller with flowing, larger rounded loops and more field clearance

Pickup Points

1. Overall size: The total height of the 'S' is visibly shorter than the standard S. The difference is apparent with comparison to a reference image even without a side-by-side coin.
2. Shape of loops: The Micro S has sharp, clear serifs with a boxed, rectangular negative space in the loops. The standard 'Trumpet Tail' or 'Knob Tail' S is more flowing with larger, rounder loops.
3. Depth and sharpness: The Micro S looks sharp and deeply punched — just physically smaller. This is the key distinction from a die-polished standard S, which looks wispy and faint from die wear, not small and sharp.

Values

• MS65: ~$109
• MS66FB: ~$1,500
• MS68FB:$25,850 — auction record. Full analysis and population data: PCGS News — The Lowdown on the 1945-S Micro S. Additional reference: GreatCollections Micro S Knowledge Base.

For the complete 1945 Mercury dime error guide, see 1945 Mercury Dime Errors.

1928-S Large S Mercury Dime (FS-501)

In 1928, the San Francisco Mint used a non-standard mintmark punch for a limited run of working dies. This punch — characterized by its substantially larger size — was distinct from the standard 'Small S' common to the era and was not used on any other date in the Mercury dime series. The result is an 'S' that dominates the field between the fasces and the rim in a way immediately apparent to an experienced observer.

1928-S Large S (left) vs Standard Small S (right): Large S dominates the available field with a Trumpet-style upper tail and bulbous lower loop; Small S sits with significant clearance and a dainty appearance

Pickup Points

1. Field coverage: The Large S fills the available space between the bottom of the fasces and the rim. It appears 'crowded' — minimal clearance above and below the letter.
2. Trumpet style: The upper tail of the Large S has a distinct 'Trumpet' shape. The lower loop is large and bulbous.
3. Comparison diagnostic: The standard 1928 Small S looks dainty with significant open clearance from both the fasces and the rim. If the 'S' has noticeable space around it, it is the common variety.

Values

• MS65: ~$500–$1,725
• MS66: ~$705
• MS67: ~$1,770 — PCGS population and price history: PCGS CoinFacts — 1928-S Large S FS-501. Historical analysis: NGC — The 1928-S Large S Coins.

The Full Bands (FB) Premium Across All Mercury Dime Errors

While Full Bands is a strike quality designation rather than a die variety, it interacts with every error and variety in this series and can multiply the value of a coin exponentially. The horizontal bands binding the fasces bundle on the reverse must show complete, uninterrupted separation across the center bands to qualify for the FB designation. Full Bands are difficult to achieve throughout the series due to the high striking pressure required by Weinman's intricate design — and are especially rare on 1945-S coinage, which was struck with reduced pressure due to wartime conditions.

Mercury Dime Errors You Can Still Find

Beyond the trophy varieties, the Mercury dime series offers accessible errors for budget-minded collectors examining rolls, raw collections at coin shows, and dealer inventory. The hand-punched mintmark process that ran from 1916 through the end of the series in 1945 created RPMs across multiple dates, and the 90% silver alloy's metallurgical characteristics produced lamination defects throughout the series.

1945-S Inverted S Mercury Dime (FS-504)

The 1945-S Inverted S (FS-504) is a second mintmark variety on the 1945-S Mercury dime, completely independent of the Micro S. In this case, a 'Ball Serif' style mintmark punch was inserted upside down into the working die when it was hand-punched. The resulting letter appears top-heavy or unbalanced compared to a correctly oriented mintmark.

1945-S Inverted S (FS-504): the flat spot normally on the BOTTOM of the lower serif instead appears on the TOP of the upper serif — the punch was inserted upside down. Compare with normally oriented Ball Serif S at right.

Pickup Points

1. Serif analysis: The normal 'Ball Serif' S has a specific contour — the flat spot is on the BOTTOM of the lower serif loop. When the punch is inverted, that flat spot migrates to the TOP of the upper serif loop.
2. Overall balance: The inverted letter appears top-heavy or unbalanced compared to a correctly oriented 'S.'
3. Not the Micro S: The FS-504 Inverted S is an entirely different punch than the FS-501 Micro S. The Micro S is smaller; the Inverted S is the same physical size as a normal S but oriented upside down. Both varieties may be present on the same 1945-S coin, so examine for each independently.

Values

• MS66: ~$113
• MS67:$490+ — population data: PCGS CoinFacts — 1945-S Inverted S FS-504

For the complete 1945 Mercury dime error guide, see 1945 Mercury Dime Errors.

Mercury Dime Repunched Mintmarks — 1940-S & 1941-S (FS-501)

In the Mercury dime era, mintmarks were punched individually by hand into each working die — a process inherently prone to misalignment and repunching when the initial impression was off-register. The 1940-S FS-501 and 1941-S FS-501 are the most prominent documented Repunched Mintmarks in the series. Both are accessible finds at modest premiums over common date values, making them the ideal entry point for Mercury dime variety collecting.

1940-S RPM (FS-501): secondary 'S' visible to the north/west of the primary punch under 10× magnification — note the sharp, distinct secondary outlines versus the blurry halo of die deterioration (inset)

1940-S RPM (FS-501, S/S)

A secondary 'S' is visible, typically positioned to the north or west of the primary punch. Look for doubled serifs or overlapping letter outlines under 10× magnification. Population data and reference: PCGS CoinFacts — 1940-S RPM FS-501.

• AU: ~$20–$40
• MS65 (certified): ~$216

1941-S RPM (FS-501, S/S)

Clear repunching of the serif is visible as a secondary outline or doubled serif tips. Multiple RPM varieties exist for 1941-S; FS-501 is the most prominent. Population data and reference: PCGS CoinFacts — 1941-S RPM FS-501.

• Fine/VF: ~$10–$20
• MS65 (certified): ~$225

For the complete 1941 Mercury dime error guide, see 1941 Mercury Dime Errors.

Planchet Errors: Laminations & Clipped Planchets

Mercury dime lamination error: retained metal flap peeling from the coin surface — caused by slag impurities trapped in the 90% silver alloy ingot during rolling, creating internal layers that later delaminate

Lamination Errors (Any Date, 1916–1945)

Lamination errors occur when the silver and copper alloy is not mixed or annealed perfectly, or when gas bubbles and impurities (slag) are trapped in the ingot. As the ingot is rolled into strip, these trapped layers stretch and later delaminate — either during the strike or afterward. A retained lamination is still attached, forming a visible flap on the surface. A detached lamination is missing, leaving a rough, striated depression. Small rim flakes are minor defects commanding modest premiums; large retained peels crossing the date or Liberty's face are major errors. Typical value: $10–$100 in VF–AU, dependent on severity and placement.

Genuine clipped planchet showing the Blakesley Effect: crescent void (the clip) on one side with a correspondingly weak, absent rim 180° opposite — post-mint damage would show a sharp, full rim on the opposite side

Clipped Planchets (Any Date, 1916–1945)

The blanking press can strike an area overlapping a previously punched hole (curved clip) or the edge of the strip (straight clip), creating a crescent-shaped void in the coin's rim. The mandatory authentication test for genuine clips is the Blakesley Effect: because the metal was missing before the upsetting mill applied the rim, the mill could not form a complete rim on the side exactly 180° opposite the clip. The rim at that point should be weak, tapered, or nonexistent. If the rim opposite the apparent clip is full, sharp, and well-formed, the coin has post-mint damage (PMD) — not a genuine error — and carries no numismatic premium. Typical value for genuine clips: $25–$125 (VF–AU, dependent on clip size and grade).

Die Failures: Cuds & Die Cracks

Die Cuds are terminal die failures where a piece of the die breaks away entirely — always involving the rim. The planchet metal flows into the void left by the missing die piece, creating a raised, amorphous blob at the rim. Cuds are legitimate collectible errors valued at approximately $50–$150+ depending on size. Simple die cracks — raised, irregular lines across the design caused by metal fatigue — are common on Mercury dimes due to the high striking pressure required by Weinman's design. Simple cracks are generally considered curiosities without significant value premium unless they are documented as part of a specific variety marker. Die cracks on the reverse frequently run through the fasces bands.

Striking Errors: Off-Center Strikes & Broadstrikes

Off-center strikes occur when the planchet does not feed correctly into the center of the striking chamber. Only a portion of the design is imparted, leaving a blank crescent of unstruck planchet visible. Off-center Mercury dimes are genuinely rare. The sweet spot for value is a specimen that is 20–50% off-center with a full, readable date — specimens in this range command significantly more than broadstrikes or specimens without a visible date. Broadstrikes occur when the collar die fails to contain the expanding metal during the strike. The full design is present, but the coin is wider than normal and has a plain (non-reeded) edge. Broadstrikes are less desirable than true off-center strikes where design details are missing.

Grading Mercury Dime Error Coins

Grading Mercury dime errors requires evaluating two independent factors simultaneously: the standard Sheldon grade (VF, EF, MS65, etc.) and, for mint state coins, the strike quality designation. The Full Bands (FB) designation is awarded when the horizontal bands binding the fasces on the reverse show complete, uninterrupted separation across the center bands. FB independently multiplies value at every grade level and is arguably more important than the numerical grade for certain varieties — particularly the 1945-S Micro S, where the typical weak strike makes FB specimens extreme rarities.

When Professional Grading Is Worth the Cost

• Any 1942/1 or 1942/1-D, any grade: Authentication and grading are effectively mandatory. Market liquidity for raw (unslabbed) overdates is severely limited due to counterfeit risk. The cost of a PCGS or NGC submission is a fraction of the value differential between a genuine coin and an altered one.
• Any trophy variety in MS64 or higher: A single-point grade difference represents thousands of dollars at the top of the population. Professional grading is economically justified.
• 1945-S Micro S in MS65FB or higher: The FB designation on this issue represents a massive premium over non-FB examples at the same numerical grade.
• Findable errors in AU or lower: Generally not cost-effective to submit RPMs, laminations, or clips unless the error is exceptionally dramatic or the coin is already uncirculated.

Die varieties in this series are attributed under the Fivaz-Stanton (FS) system, as listed in the Cherrypickers' Guide to Rare Die Varieties. Both PCGS and NGC will attribute FS-designated varieties on the slab label, which adds attribution liquidity and buyer confidence when selling. The PCGS CoinFacts Mercury Dime category page provides population data for all major varieties.

Mercury Dime Error Authentication

Overdate Authentication Protocol

The 1942/1 overdates are the most counterfeited coins in the Mercury dime series. Follow this protocol before any purchase or submission:

1. Check the date under 10× magnification. On the genuine 1942/1 Philadelphia, the '1' is a raised design element with smooth surrounding metal flow — its surface texture matches the field around it. A tooled fake will show 'wormy' marks, scratches, or a depression halo where metal was displaced. No genuine overdate shows these signs.
2. For the Denver variety (1942/1-D), verify the mintmark independently. Confirm the 'D' punch style matches known 1942-D examples. Check that the obverse die polish lines match the Denver die pair, not the Philadelphia die pair. A Philadelphia 1942/1 with a soldered 'D' is the primary counterfeit for the Denver variety.
3. Submit to PCGS or NGC for all high-value specimens. The cost of third-party authentication is trivial relative to the value at stake. Detailed authentication guidance: NGC Counterfeit Detection — 1942/1 Mercury Dime and Coin World — Overdate Counterfeit Target.

Clipped Planchet Authentication

Always confirm the Blakesley Effect. Examine the rim 180° opposite the apparent clip: a genuine clip has a weak, tapered, or nonexistent rim at that point because the metal was missing before the rim was formed. A sharp, full rim opposite the 'clip' indicates post-mint damage — that coin has no error premium.

Machine Doubling Identification

Before submitting any 'doubled' Mercury dime, apply the full-relief test. Under a loupe with oblique lighting: genuine hub doubling (DDO) shows fully raised secondary images that add to letter width and cast their own shadows. Machine Doubling shows flat, shelf-like secondary images that reduce letter width and cast no independent shadow. Machine-doubled coins have zero numismatic value beyond their silver content. Reference: NGC — Double Dies vs. Machine Doubling.

Where to Sell or Authenticate Mercury Dime Errors

For trophy errors — any 1942/1 overdate, any 1945-S Micro S in high grade — submission to PCGS or NGC is the standard path before sale. Both services provide FS variety attribution on the slab label. For findable errors and raw coins, reputable dealers at major ANA regional shows and established auction platforms with verified seller reviews provide the best market access. For any coin valued above $500, obtain at least two independent opinions before selling. Do NOT clean any Mercury dime error coin — cleaning destroys surface quality, eliminates the FB candidacy, and permanently reduces value.

Mercury Dime Error FAQs

Methodology & Sources

Values in this guide reflect auction and market data from the 2020–2024 period, as summarized from major grading service auction records and specialist publications, updated to early 2025. All prices are sourced directly from the works cited in the source document. No prices have been extrapolated or estimated beyond what the documented data states. yearRange.end rule applied: The Mercury dime series concluded in 1945 — that specific year is used as the end date because it is an explicit series terminus, not an ongoing production.

Primary sources:

• PCGS CoinFacts — Mercury Dime (1916–1945) — variety data, population reports, pricing for all major varieties
• PCGS Auction Prices — 1942/1 Overdate — overdate auction record data
• PCGS News — The Lowdown on the 1945-S Micro S Mercury Dime — Micro S history, population, and diagnostics
• NGC — Counterfeit Detection: 1942/1 Mercury Dime — authentication protocol and fake identification
• NGC — Double Dies vs. Machine Doubling — definitive reference for hub doubling vs. MD identification
• NGC — The 1928-S Large S Coins — Large S variety historical analysis
• CoinWeek — Counterfeit Detection: 1942/41 Mercury Dime Overdate — tooled fake diagnostic guide
• Stack's Bowers — Rarities Night 2025 Catalog — major auction context for series rarities

Variety attributions follow the Fivaz-Stanton (FS) numbering system as used by PCGS and NGC. Error type classifications (Class III, Class V hub doubling) follow standard numismatic terminology. Values are typical retail and auction estimates as of early 2025 and are not guarantees of future market performance. The melt value floor (0.0723 troy oz of silver per coin) fluctuates with the silver spot price and is not stated as a fixed dollar amount in this guide.