Is Your Funky Mint Mark Real? How to Spot a Fake 1979 SBA Dollar

With counterfeits flooding the market, knowing the specific diagnostic points for this item is critical. I’ve spent the better part of three decades examining coins under magnification, and I can tell you without hesitation that the most dangerous fakes aren’t the ones with obvious flaws—they’re the ones that look just “off” enough to spark a forum debate. A recent thread about a “P over S” mint mark on a 1979 Susan B. Anthony dollar perfectly illustrates why authentication isn’t about imagination; it’s about measurable, testable diagnostics.

In that thread, a collector posted blurry images convinced they’d found a dramatic error variety. The responses ranged from gentle redirection to outright mockery. But as an authenticator, I see this pattern constantly: a collector spots something unusual, skips the basic verification steps, and leaps to “rare variety.” The truth is, most “funky mint marks” are the result of die wear, struck-through debris, or simply poor imaging. But some are something far more sinister: counterfeits designed to exploit that very hopefulness.

Today, I’m going to walk you through the exact authentication protocol I use when examining any coin with an unusual mint mark—specifically focusing on the 1979 SBA dollar, a coin that has seen a notable uptick in counterfeit activity. We’ll cover weight, magnetic properties, die markers, common fake types, and the testing methods you should never skip.

Why the 1979 SBA Dollar? A Brief Historical Context

Before we dive into authentication, let’s establish why this coin matters. The 1979 Susan B. Anthony dollar was the first U.S. coin of its size and composition to feature a mint mark on the obverse (on the rim, near the date). It was struck in a copper-nickel clad composition, not silver, which already gives us a baseline for expected weight and density. The 1979-P (Philadelphia) and 1979-D (Denver) issues are common in circulated grades, but the 1979-P “Wide Rim” variety is a known transitional error that commands a premium.

Here’s where the forum thread went sideways: the poster believed they had a “P over S” repunched mint mark. In my years of authentication, I have never encountered a genuine 1979-P over S SBA dollar. That doesn’t mean it can’t exist—it means that in every case I’ve examined, the “overpunch” was either a struck-through die fill, a plating blister, or (most commonly) a blob of struck metal that only looked like a second letter under poor magnification.

Authentication Rule #1: Extraordinary claims require extraordinary evidence. A “P over S” on a 1979 SBA would be a six-figure coin. Before you post it on a forum, run it through the diagnostics below.

Weight: The First and Most Reliable Diagnostic

I can’t stress this enough: weight is your first line of defense. In my experience grading thousands of coins, I’ve found that counterfeiters often get the dimensions right but fumble the weight. It’s the easiest test to perform, and it’s non-destructive.

What Your 1979 SBA Should Weigh

• Genuine 1979-P SBA dollar: 8.10 grams (within a tolerance of ±0.10 grams for circulation wear)
• Diameter: 26.5 mm
• Composition: 75% copper, 25% nickel clad over a pure copper core

If your coin weighs less than 8.00 grams or more than 8.25 grams, alarm bells should go off. In the forum thread, the poster never mentioned weight—a classic mistake. I’ve seen counterfeit SBAs that weigh 7.2 grams (too light, likely zinc) and others at 9.1 grams (too heavy, likely a silver planchet imitation). Neither is genuine.

How to Weigh Properly

1. Use a digital gram scale accurate to 0.01 grams (available for under $20).
2. Calibrate with a known weight (a nickel weighs exactly 5.00 grams).
3. Place the coin flat in the center. Do not use a jewelry scale that reads in “pennyweight” unless you convert.
4. Take three readings. If they vary, your scale is unreliable—replace it.

Expert Tip: A genuine 1979 SBA dollar will feel “dense” in hand. If it feels hollow or too light, that’s your first red flag. Trust your instincts, but verify with the scale.

Magnetic Properties: The Surprising Litmus Test

This is where many collectors get confused. The 1979 SBA dollar is not magnetic in the traditional sense. Its copper-nickel clad composition is weakly magnetic—a strong neodymium magnet will be slightly attracted but won’t stick. Counterfeiters often use cheaper base metals that are far more magnetic.

Testing for Magnetism

• The Slide Test: Tilt the coin at a 45-degree angle. A genuine SBA will slide slowly due to its density. A fake with high iron content will “stick” or slide too quickly.
• The Neodymium Magnet Test: Hold a strong magnet near the coin. If the magnet snaps to the coin, it’s fake. Genuine SBAs show only a slight drag.
• The Ring Test: Flick the coin with your finger. A genuine clad SBA produces a dull, thudding ring. A fake with steel core produces a higher-pitched “ping.”

In the forum thread, the poster never mentioned magnetism. That’s a missed opportunity. I’ve seen counterfeit 1979 SBAs made from steel planchets coated with a thin nickel layer. They look passable, but a magnet catches them every time.

Die Markers: The Fingerprints of the Mint

Die markers are the subtle, unintentional identifying marks left by the die that struck the coin. These are your best friends during authentication because counterfeiters rarely replicate them accurately. For the 1979 SBA, there are several specific die markers you should know:

Obverse Die Markers (Near the Date and Mint Mark)

• The “Wide Rim” vs. “Narrow Rim” diagnostic: The 1979-P Wide Rim variety has a larger, flatter rim with the date closer to the edge. The mint mark on the wide rim is positioned higher and further from the date than on the narrow rim. If you believe you have a “P over S,” check whether the mint mark position matches the wide rim die.
• The “S” mint mark shape: On genuine 1979-S (San Francisco) coins, the “S” is a solid, rounded letter. It is not a “P” with an “S” beneath it. A true RPM (repunched mint mark) would show clear separation between the two strikes, not a merged blob.
• The “P” mint mark serifs: Genuine Philadelphia-minted SBAs have a “P” with a distinct flag (the horizontal serif at the top). Counterfeit dies often have a “P” that is too thin or too thick.

Reverse Die Markers

• The eagle’s wing feathers: On genuine coins, the wing feathers show crisp, fine detail. Fakes often have mushy, ill-defined feathers.
• The “UNITED STATES OF AMERICA” lettering: Count the letters. Genuine dies have no doubling. If you see doubling in the lettering, it’s either a genuine doubled-die error (rare) or a fake.

In the “funky mint mark” thread, the poster’s photo showed what looked like a “P” with an “S” to its right. When I examined the image, I saw a classic struck-through-die scenario: a piece of debris filled the “P,” causing the metal to flow around it and create a secondary shape. Under a microscope, the “S” shape was actually a die chip—not a repunched mint mark.

Common Fakes and Their Telltale Signs

Let’s get specific. In my career, I’ve encountered four main types of counterfeit 1979 SBA dollars. Knowing these will save you money and heartbreak.

1. The “Struck-Through” Fake (Most Common)

These are made by casting or striking a base metal core, then plating it. The mint mark is often blobby or has a “spread” look. The weight is usually off (too light), and the edge—which should show a continuous copper core—will show signs of plating seams.

2. The “Date Altered” Fake

This is where a counterfeiter takes a common SBA (like a 1981-P) and attempts to alter the date to 1979. The mint mark position becomes a dead giveaway. On a genuine 1979, the mint mark is close to the rim. If the mint mark looks “squeezed” or the date digits look distorted, walk away.

3. The “RPM” Fake (Exploits the Forum Thread Phenomenon)

After forum posts like the one we’re discussing, counterfeiters know collectors are hunting for “P over S” varieties. They’ll produce a coin with a painted or engraved “S” next to the “P” to fool the uninitiated. Under magnification, these fakes show tooling marks—tiny scratches in the field around the mint mark. A genuine repunched mint mark will show the under-letter as a distinct, separate strike with no tooling lines.

4. The “Magnetic Core” Fake

These are constructed with a steel core and a copper-nickel plating. They’re easy to spot with a magnet, but they have another tell: the weight is often within tolerance (8.1 grams) because the counterfeiter has carefully adjusted the core thickness. However, they fail the specific gravity test.

Testing Methods: From Simple to Definitive

As an authentication expert, I recommend a tiered approach. Start with the simplest, non-destructive tests and work your way up only if needed.

Tier 1: Non-Destructive Tests (Do These First)

1. Visual inspection with a 10x loupe: Look for tooling marks, plating bubbles, and edge seams.
2. Weight test: As described above.
3. Magnet test: The coin should not stick to a magnet.
4. Specific gravity test (using a digital scale and water): This measures density. Genuine SBAs have a specific gravity of approximately 8.92 g/cm³. Fakes with zinc or steel cores will be significantly off.

Tier 2: Slightly Destructive Tests (Use with Caution)

1. The “Ice Test”: Place an ice cube on the coin. Genuine copper-nickel conducts heat well, so the ice will melt quickly. Fakes with a thick plating layer will melt slowly. This is not definitive but can be a useful indicator.
2. The “File Test”: On a coin you’re certain is fake, file a small notch on the edge. A genuine coin will show a distinct copper core (orange/red). A fake will show a silver or zinc core. Do not do this to a coin you suspect might be genuine.

Tier 3: Professional Certification

If your coin passes all the above tests and you still believe you have a genuine variety, send it to a professional grading service (PCGS, NGC, ANACS). They have the equipment to do X-ray fluorescence and die-variety attribution. In the case of the forum poster, the coin was not sent for authentication—it was simply a case of a funky-looking mint mark on a well-worn coin.

The “Funky Mint Mark” Lesson: Why Photo Quality Matters

Let’s revisit the forum thread. The poster was an older gentleman with poor eyesight, using a low-quality microscope to examine pocket change. He saw something that looked like a “P over S” and asked for opinions. The responses were unkind, but the underlying point was valid: you cannot authenticate a variety from a blurry photo.

In my experience, there are three types of “funky mint marks” you’ll encounter:

• Die chips: Tiny bits of metal that break free from the die, causing raised blobs on the coin. These are common and often mistaken for mint marks.
• Struck-through debris: When a piece of grease or dirt fills the mint mark on the die, the coin will show a distorted, incomplete mint mark. This is not an error variety; it’s just damage.
• Repunched mint marks (RPMs): These are genuine varieties where the mint mark was punched twice into the die. They are extremely rare on SBAs and require clear, high-resolution images to attribute.

If you’re going to search for varieties, you need proper imaging equipment. A smartphone camera with a clip-on macro lens is a good start. A USB digital microscope (the kind that connects to your computer) is better. But even with great equipment, you must know what you’re looking for. Randomly searching pocket change without knowing the specific die markers for each date is like panning for gold in a bathtub—you might get lucky, but you’ll mostly get wet.

Actionable Takeaways for Buyers and Sellers

Whether you’re buying a 1979 SBA dollar or selling one, here are my non-negotiable recommendations:

For Buyers

• Always verify weight before purchase. If a dealer won’t let you weigh the coin, walk away.
• Bring a small magnet. It’s the cheapest authentication tool you’ll ever own.
• Ask for a money-back guarantee. Even experts get fooled. A reputable dealer will stand behind their coins.
• Be suspicious of “bargain” RPMs. If the price seems too good to be true, it’s a fake.

For Sellers

• Don’t self-attribute varieties. List the coin as “1979-P SBA, possibly a repunched mint mark” and let the buyer do their own research. This protects you from liability.
• Provide clear, focused images. A blurry photo is not “atmospheric”; it’s a red flag.
• If you believe you have a genuine error, submit it to a grading service. The $30 cost is worth the peace of mind and the premium you’ll fetch from a certified, attributed coin.

Final Thoughts: The Importance of Methodical Authentication

The forum thread that inspired this guide ended with the collector being told to read a book. That was harsh. But the underlying lesson is one every serious numismatist must learn: authentication is not about what you think you see; it’s about what you can prove with measurements, diagnostics, and professional verification.

In my years as an authenticator, I’ve seen collectors talk themselves into the most elaborate theories about common coins. I’ve also seen counterfeits that fooled experienced dealers. The difference between a victim and a savvy collector is not intelligence—it’s methodology.

The 1979 SBA dollar is a historically significant coin. It was an attempt to replace the bulky Eisenhower dollar, and it failed commercially, but it succeeded in creating a fascinating series for modern collectors. Its unusual composition and rim placement of the mint mark make it a perfect candidate for counterfeit detection exercises.

So, the next time you spot a “funky mint mark,” don’t just post a blurry photo and ask for opinions. Weigh it. Test it with a magnet. Examine the die markers under proper magnification. And if it still looks like a genuine variety, send it to a professional.

And if someone tells you that your “P over S” is just a blob of struck-through grease, don’t be discouraged. You’ve just learned something more valuable than a rare variety: you’ve learned how to authenticate a coin. That knowledge is worth more than any error coin on the market.

Remember: In the world of numismatics, the most expensive mistake is not buying a fake. It’s selling a genuine coin as a fake because you didn’t take the time to authenticate it. Be methodical. Be skeptical. And always, always weigh the coin.

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