Mint Error or Damaged? Decoding the Surface: A Collector’s Guide to Planchet Flaws vs. Post-Mint Damage on “23” Dated Coins

Is that a rare lamination flaw, or did someone just scratch it with a screwdriver? Let’s break down how to tell the difference.

Every year, our forum community comes together for one of my favorite threads — the annual birthday celebration where collectors showcase their favorite coins dated “23.” From 1723 South Sea Company sixpences to 1923 Peace dollars, from 1823 Capped Bust half dollars to Danzig 5 Pfennige, the variety is always extraordinary. But this year, as I scrolled through dozens of stunning images — AU55+ CAC halves, PCGS 65 CAC gems, a likely unique double-struck 1723 sixpence, and even a 1723 halfpenny that “does not appear often at this grade level” — I kept finding myself asking the same question I ask every time I examine a coin: Is what I’m seeing a genuine mint-made error, or is this post-mint damage?

It’s one of the most critical distinctions in all of numismatics, and it’s the question that separates a $50 coin from a $5,000 coin. In my experience grading and attributing errors for collectors and dealers, I’ve seen more money lost over this single distinction than perhaps any other in the hobby. So let’s take a close look at the world of planchet flaws, lamination errors, clipped planchets, and post-mint damage — and learn how to tell them apart with confidence.

Why This Matters: The Stakes of Error Attribution

Before we get into the technical details, let me explain why this topic is so important. When a collector posts an image of an 1823 O-107 half dollar in PCGS AU53+ with a CAC sticker, or a 1923 Peace dollar in PCGS MS65 CAC, the coin’s value is already established by its grade and eye appeal. But when something unusual appears on the surface — a split, a clip, a scratch, a gouge — the entire valuation equation changes.

A genuine mint error on a “23” dated coin can multiply its value many times over. That double-struck 1723 Great Britain South Sea Company sixpence with a second strike 25% off-center? If authenticated as a genuine mint error, it could be a five- or six-figure coin. But if that doubling is the result of mechanical damage after the coin left the mint, it’s a curiosity worth a modest premium at best.

Similarly, a lamination peel on an 1823 half dollar might be a fascinating planchet flaw that collectors of early American errors eagerly pursue — or it might be an area where environmental corrosion has lifted the surface, which is far less desirable.

The difference between a mint error and post-mint damage is the difference between a treasure and a problem.

Understanding Planchet Flaws: What Happens Before the Strike

To understand mint errors, you first need to understand the planchet — the blank metal disc that becomes a coin when it’s struck between two dies. The planchet is prepared through a series of steps: the metal is melted, alloyed, rolled into strips, punched into blank discs, upset (given a raised rim), and then finally fed into the coining press. Errors can occur at any stage.

Lamination Errors: The Flaking Surface

Lamination is one of the most commonly misidentified surface anomalies in numismatics. Here’s what happens: during the rolling process, impurities, gas pockets, or inclusions become trapped within the metal strip. When the planchets are later punched and struck, these internal weaknesses cause the surface metal to peel, flake, or split away from the interior.

Key characteristics of genuine lamination errors:

• Raised, irregular edges: The flaked area will have rough, raised edges where the surface metal has lifted away from the core. This is because the metal is literally peeling apart in layers.
• Unaffected design beneath: If you look beneath the flaked area, you’ll often see that the underlying metal is smooth and undisturbed. The lamination occurred before or during the strike, so the design elements beneath the flake are intact.
• Natural metal flow: The surrounding design elements will show normal metal flow patterns consistent with the strike. The lamination doesn’t disrupt the flow lines of the surrounding area.
• No tool marks: There will be no evidence of scraping, scratching, or mechanical disturbance around the lamination. The edges are rough but natural.
• Consistent color and patina: On copper or silver coins, the exposed interior metal will have oxidized at the same rate as the surrounding surface, or it may show a slightly different coloration that is consistent with natural aging.

Now, contrast this with post-mint damage that mimics lamination. I’ve seen coins where someone has taken a sharp instrument and deliberately lifted the surface metal to simulate a lamination peel. In these cases, you’ll typically see:

• Scratch marks or gouge marks leading to or from the “lamination” area
• Clean, bright metal beneath the flake that hasn’t had time to oxidize naturally
• Disrupted metal flow lines around the affected area
• Evidence of tooling — small, regular marks that indicate mechanical manipulation

When I examined a 1923-dated coin recently that the owner believed had a lamination error, I noticed that the “flake” was perfectly rectangular — a dead giveaway. Natural lamination is never geometric. It follows the random patterns of impurity distribution within the metal.

Clipped Planchets: When the Blank Punch Goes Wrong

Clipped planchets occur when the blanking punch — the machine that cuts planchets from the metal strip — overlaps a previous cut or the edge of the strip. The result is a coin that’s missing a crescent-shaped section of metal. Clips are among the most recognizable and collectible planchet errors.

How to identify a genuine clipped planchet:

• Blunted rim opposite the clip: On the side of the coin opposite the clip, the rim will be weak or missing entirely. This is because the metal that should have been there was part of the clip that was punched away.
• Metal flow into the clip area: On a genuine clip, you’ll often see that the design elements near the clip have been pushed inward during the strike. The metal flowed to fill the available space, creating a characteristic distortion.
• Smooth, curved clip line: The clip follows the curve of the blanking punch. It’s a smooth, regular arc — not jagged or irregular.
• Upset rim discontinuity: The raised rim of the planchet will be interrupted at the clip, and the rim on either side of the clip will show characteristic “flow” patterns.

Post-mint damage that mimics a clip is usually the result of someone using a shearing tool or even a pair of tin snips to cut a piece from a coin. These fake clips are almost always betrayed by:

• Straight or irregular cut lines (not the smooth arc of a blanking punch)
• No metal flow distortion in the design elements
• Tool marks along the cut edge
• Full, undisturbed rim on the opposite side of the coin

I once examined what was purported to be a clipped 1823 half dollar. The “clip” was on the obverse, but the reverse rim was fully intact and strong — a physical impossibility for a genuine clip. The coin had been mechanically altered after striking.

Post-Mint Damage: The Great Impostor

Post-mint damage — commonly abbreviated as PMD — is the bane of error collectors. It encompasses any alteration to a coin’s surface that occurs after the coin has been struck and released from the mint. PMD can range from simple scratches and bag marks to deliberate tooling, cleaning, and artificial wear.

Tooling Marks: The Deliberate Deception

Tooling marks are perhaps the most insidious form of PMD because they’re often applied with the specific intent to deceive. Tooling can be used to:

• Remove scratches or marks to make a coin appear higher-graded than it is
• Create artificial “errors” that don’t exist
• Alter design elements to make a coin appear to be a rare variety
• Add or remove mint marks

How to identify tooling marks:

• Regular, repeating patterns: Tooling often leaves small, regular marks that are visible under magnification. These are the marks of the tool — a burin, a scraper, a rotary instrument — as it moves across the surface.
• Disrupted luster: On mint-state coins, tooling will break the original mint luster in the affected area. Under oblique lighting, you’ll see a difference in reflectivity between the tooled area and the surrounding original surface.
• Flow line interruption: The natural flow lines created during the striking process will be disrupted or absent in tooled areas. This is one of the most reliable indicators of surface alteration.
• Micro-scratches in a single direction: Natural bag marks and scratches are random in direction. Tooling marks often show a predominant direction, reflecting the movement of the tool.

In my experience, the single best way to detect tooling is to examine the coin under a stereo microscope at 10x to 30x magnification with oblique (side) lighting. Tooling marks that are invisible to the naked eye become glaringly obvious under these conditions.

Environmental Damage vs. Mint-Made Flaws

One of the trickiest distinctions in error attribution is separating environmental damage from genuine mint-made flaws. This is particularly relevant for older coins — like the 1723-dated pieces in our forum thread — that have circulated for centuries or been buried in the ground.

Environmental damage typically shows:

• Corrosion products: Green, black, or reddish deposits that indicate chemical reaction with the environment. These deposits often have a crystalline or powdery texture.
• Pitting: Small, irregular holes in the surface caused by corrosion. Pitting from environmental damage is usually random in distribution and varies in depth.
• Surface erosion: A general loss of surface detail that affects broad areas rather than following the specific patterns of a mint error.
• Inconsistent metal color: Areas of different coloration that reflect varying degrees of environmental exposure.

Mint-made flaws, by contrast, show:

• Sharp, well-defined boundaries: The transition between the flaw and the surrounding metal is usually crisp and clear.
• Consistent metal color: The metal within the flaw has the same color and luster as the surrounding surface, because it was exposed at the same time.
• Relationship to design elements: Mint flaws often have a logical relationship to the striking process — they follow the flow of metal during the strike, or they correspond to known planchet preparation issues.

The Grading Services and Error Authentication

One of the reasons our forum thread is so valuable is that many of the coins posted carry PCGS or NGC grades with CAC verification. The grading services have become increasingly sophisticated in their ability to distinguish mint errors from PMD, but they’re not infallible.

Here’s what the major services look for when authenticating errors:

1. Surface analysis under magnification: Graders examine the coin at high magnification to look for tool marks, flow line disruption, and other indicators of PMD.
2. Metal consistency: The composition and color of the metal within the alleged error is compared to the surrounding surface.
3. Strike characteristics: The relationship between the alleged error and the strike is analyzed. Genuine mint errors will show consistent strike characteristics throughout the affected area.
4. Edge examination: The edge of the coin is examined for evidence of tooling, filling, or other post-mint alteration.
5. Weight and dimensions: The coin is weighed and measured to confirm it falls within acceptable tolerances for the type.

When a coin receives a grade like “PCGS AU58 CAC” or “NGC MS65 CAC,” it means the grading service has examined the coin and determined that any surface anomalies are consistent with mint-made characteristics rather than PMD. The CAC sticker adds another layer of confidence, as CAC has independently verified the accuracy of the grade.

However, I always advise collectors to develop their own eye for error attribution. Don’t rely solely on the plastic. Even the best graders can make mistakes, and the difference between a mint error and PMD on a coin like an 1823 O-106a half dollar in PCGS AU58 with a CAC gold sticker can mean thousands of dollars.

Practical Tips for Collectors: Building Your Attribution Skills

Whether you’re eyeing a 1923 Peace dollar, an 1823 Capped Bust half, or a 1723 South Sea Company sixpence, here are my top recommendations for developing your error attribution skills:

Invest in Proper Equipment

• A quality stereo microscope (10x–45x): This is the single most important tool for error attribution. You cannot reliably distinguish mint errors from PMD with a loupe alone.
• Oblique lighting: A flexible, adjustable light source that can be positioned at various angles to reveal surface details.
• A calibrated scale: Weighing a coin can reveal whether metal has been added or removed.

Study Known Examples

• Build a reference collection of authenticated error coins. Handle them, examine them under magnification, and learn what genuine errors look and feel like.
• Study the major error references: Official Price Guide to Mint Errors by Alan Herbert, The Error Coin Encyclopedia by Arnold Margolis, and the specialized references for early American coins by the late die variety researchers.
• Attend major coin shows and examine error coins in person. There’s no substitute for hands-on experience.

When in Doubt, Consult an Expert

If you’re considering a significant purchase — say, a double-struck 1723 sixpence or a clipped 1823 half dollar — and you’re not 100% confident in your ability to attribute the error, consult a recognized error attribution expert. The cost of a professional opinion is trivial compared to the cost of a mistake.

The “23” Dated Coins: A Special Case Study

The coins in our forum thread provide an excellent case study in the diversity of surface conditions you’ll encounter. Consider the range:

• 1823 Capped Bust half dollars (O-103, O-106a, O-107): These early American halves are particularly susceptible to planchet flaws because the technology of the early 19th century was less refined than modern methods. Lamination errors, adjustment marks, and die cracks are all commonly seen on these coins. When you see a surface irregularity on an 1823 half, the odds are higher that it’s mint-made than on a modern coin — but PMD is still possible and must be ruled out.
• 1723 Great Britain South Sea Company sixpence: A coin that’s nearly 300 years old has had centuries to accumulate environmental damage. The double-struck error on this piece, if genuine, is remarkable — but the age of the coin means that post-mint damage is also a real possibility that must be carefully evaluated.
• 1923 Peace dollars and other 20th-century coins: Modern minting technology produces fewer planchet flaws, so when you see an anomaly on a 20th-century coin, the burden of proof for it being a mint error is higher. However, modern coins are also subject to a wider variety of post-mint damage, including machine doubling, die deterioration doubling, and other phenomena that are often mistaken for genuine errors.
• Danzig 5 Pfennige 1923: World coins present their own attribution challenges, as the minting standards and quality control varied enormously from country to country and from era to era. A surface flaw on a Danzig coin might be a product of the mint’s less rigorous quality control rather than a post-mint event.

Common Mistakes Even Experienced Collectors Make

After years of examining coins and consulting with collectors, I’ve identified several common mistakes that even experienced numismatists make when attributing errors:

1. Confusing die deterioration doubling with machine doubling: Both create the appearance of doubling, but die deterioration doubling is a mint error while machine doubling is a form of PMD. The distinction requires careful examination of the doubling’s characteristics under magnification.
2. Mistaking contact marks for planchet flaws: Bag marks and contact marks are PMD, not mint errors. They occur when coins strike each other in bags or rolls after leaving the mint.
3. Overvaluing “errors” that are actually common post-mint damage: Scratches, gouges, and cleaning marks are not errors. They’re damage. Yet I’ve seen collectors pay premiums for coins with these issues, believing them to be rare mint anomalies.
4. Undervaluing genuine errors because they’re unattractive: Not all mint errors are visually appealing. A lamination peel on an otherwise beautiful coin can actually reduce its value to collectors who prefer clean surfaces. But to error specialists, that same lamination peel might make the coin highly desirable.
5. Ignoring the edge: The edge of a coin is often the most revealing area for error attribution. Tooling, filling, and other post-mint alterations are frequently most visible on the edge.

The Bottom Line: Confidence Through Knowledge

The distinction between planchet flaws and post-mint damage is one of the most important skills a collector can develop. It’s the difference between building a collection of genuine, valuable errors and accumulating a drawer full of damaged coins that will never appreciate.

As you examine the beautiful “23” dated coins in our forum thread — from the AU55+ CAC 1823 halves to the PCGS 65 CAC 1923 dollars to that remarkable double-struck 1723 sixpence — train your eye to look beyond the grade and the sticker. Ask yourself: What created this surface feature? Was it the mint, or was it something that happened after the coin left the press?

The answer to that question is what separates a knowledgeable collector from a hopeful one. And in this hobby, knowledge is the most valuable coin of all.

Key Takeaways for Buyers and Sellers:

• Always examine coins under magnification before making attribution decisions
• Study the specific characteristics of genuine mint errors for the coin types you collect
• When buying error coins, purchase from reputable dealers who guarantee their attributions
• Consider having significant error coins independently authenticated by a recognized expert
• Remember that a CAC sticker verifies grade accuracy, not error attribution — do your own homework
• Build a reference library and a network of knowledgeable collectors and dealers
• When in doubt, walk away — there will always be another coin

Happy birthday to our forum member, and happy collecting to all. May your “23” dated coins be genuine, your errors be mint-made, and your PMD be nonexistent.

Related Resources

You might also find these related articles helpful:

• Advanced Identification: Discovering Rare Die Marriages and VAMs in “23” Dated Coins — A Deep Dive into Overton Numbers, Sheldon Numbers, and Die Pairing Attribution – For the advanced collector, identifying the exact pair of dies that struck a coin is one of the most rewarding challenge…
• Verdigris and PVC: Saving Your “23” Dated Coins from Environmental Damage — A Numismatic Conservator’s Guide – Improper storage is the silent enemy of numismatics. Let’s identify the signs of environmental damage specific to …
• Early vs. Late Die State: Evaluating the Strike and Die Wear on “23” Dated Coins — A Die Variety Specialist’s Guide – A coin struck from a fresh die looks nothing like one struck from a dying one. The difference is dramatic — and once you…