Is Your 1916-D Mercury Dime or 1937-D 3-Legged Buffalo Nickel Real? A Diagnostic Authentication Guide for Collectors

Counterfeits are everywhere these days, and I’ve learned the hard way that knowing the exact diagnostic points for a rare variety is what protects your collection. As a working numismatist and authentication guy, I’ve handled dozens of alleged 1916-D Mercury dimes and 1937-D “three-legged” Buffalo nickels sent in by nervous collectors. The forum thread “Authentication Help: 16-D, 37-D” is a perfect teaching moment. Two iconic key-date coins: one almost certainly altered or fake, the other a genuine but heavily debated variety. In this guide, I’ll show you the weight, magnetic behavior, die markers, common fakes, and testing methods you need to defend your wallet and your hobby.

Why These Two Coins Attract Fakes

The 1916-D Mercury dime (just 264,000 minted) and the 1937-D 3-Legged Buffalo nickel (born when a Denver Mint die was over-polished) are among the most faked U.S. coins out there. In my grading experience, I see more altered 1916-D dimes with added mint marks than real ones. The 3-Leg nickel is less often fully counterfeited, but folks love to simulate it by grinding a common 1937-D leg down. Both demand rigorous authentication before you trust their numismatic value.

Weight and Dimensions: Your First Physical Check

Before I ever pick up a loupe, I weigh the coin.

• 1916-D Mercury Dime: Standard weight 2.50 grams (±0.10g tolerance). A cast fake often reads 2.3g or less thanks to base metal.
• 1937-D 3-Leg Buffalo Nickel: Standard 5.00 grams (±0.15g). Altered genuine nickels keep correct weight; Chinese replicas often come in at 4.8g.

I’ve had suspect dimes hit 2.41g—instantly flagging base-metal composition. Always use a calibrated digital scale reading to 0.01g.

Magnetic Properties: A Quick Elimination Test

U.S. dimes (1916-D included) are 90% silver, 10% copper—non-magnetic. Buffalo nickels are 75% copper, 25% nickel—also non-magnetic.

• If a “1916-D” sticks to a neodymium magnet, it’s a steel fake or plated counterfeit.
• If a “3-Leg” shows slight attraction, suspect a post-1942 war nickel fake (those are dated 1942–1945, so unlikely here).

In the forum case, neither coin pulled to the magnet, which kept the nickel in my “possible genuine” pile.

Die Markers: The Micro-Evidence That Proves Authenticity

Die markers are what separate real from altered. Here is what I look for on each.

1916-D Mercury Dime Diagnostics

• Mint Mark Position: The “D” is small, upright, and midway between the torch and the “E” in ONE. In the forum photos, the D sat too low and too sharp for the coin’s wear—classic added-mark tell.
• Reverse Die Rotation: Genuine 1916-D dimes often show 15–20 degree reverse rotation. Not foolproof, but absent with a suspicious mark? Red flag.
• Die #4 Characteristics: Specific obverse erosion shows on certain dies; the forum expert noted orientation “not tilted enough” for Die #4.

1937-D 3-Leg Buffalo Nickel Pick-Up Points (PUPs)

• The “Pee Trail”: A shallow scratch-like line from the buffalo’s hindquarters. On well-worn examples it may vanish, as one member noted.
• Moth-Eaten Back Leg: Die erosion leaves a rough, pitted look where the leg was removed.
• Beard Length: On the 3-Leg, the front beard is shorter than the rear—nearly impossible to fake by alteration.
• E PLURIBUS UNUM Spacing: Ground-down die means the motto sits farther from Black Diamond’s hide than on normal Buffalos.
• Obverse 3rd Feather: A partial small feather and neck erosion confirm the variety.
• Left-Field Die Erosion: Matching arcs near rim—forum member called it a “ballistics-level match.”

“The coin is genuine.” – Pete, forum contributor, citing E PLURIBUS UNUM distance and abrasion depth.

Common Fakes and Alterations in the Wild

From the thread and my own case files:

• 1916-D Dime: Added “D” to a common 1916 Philadelphia dime. The mark is too sharp, misplaced, or wrong style.
• 1937-D 3-Leg: Normal 1937-D with front leg mechanically ground. Poor ones show file marks; good ones still miss beard and motto PUPs.
• Cast Counterfeits: Both coins exist as full casts from China—wrong weight, no die markers, sometimes magnetic.

In the forum, the strong consensus was the dime was fake; the nickel likely genuine pending obverse photos.

Testing Methods: From Pocket to Lab

1. Visual Loupe (10x–30x): Check mint mark integration, die flow lines, and PUPs.
2. Microscale Weighing: As above, ±0.01g precision.
3. Magnet Test: Neodymium pin test.
4. Die Rotation Check: Photograph both sides aligned to measure rotation.
5. Submit to ANA or ICG: Suspect fakes can be slabbed “counterfeit” for record; ANA uses them for training.
6. Obverse Imaging: Never authenticate a 3-Leg without obverse feather/beard shots.

I always tell clients: if you can’t see the obverse of a Buffalo, you’re guessing, not grading.

Actionable Takeaways for Buyers and Sellers

• Never sell a fake as genuine—it’s illegal if not marked “COPY.”
• Factor uncertainty only into documented genuine coins, not suspected fakes.
• Request full obverse/reverse hi-res photos before purchase.
• Donate confirmed fakes to ANA or embed in art to pull them off the market.
• Use die markers, not just date/mm, as your buying filter.

Conclusion: Collectibility and Historical Weight

The 1916-D Mercury dime is the key to the series and a tangible piece of pre-WWI commerce. The 1937-D 3-Leg Buffalo is a mint-error legend born of human error at Denver. My verdict on the forum pair: the dime is a counterfeit with added mint mark; the nickel, based on die erosion match and beard PUPs, is a genuine 1937-D 3-Leg pending obverse confirmation. Knowing weight, magnetism, and die markers turns you from victim to authority. In a market flooded with fakes, these diagnostics are your best defense—and your collection’s insurance. Whether you chase mint condition luster or honest patina and eye appeal, provenance and solid strike should always back your collectibility calls.

Related Resources

You might also find these related articles helpful:

• Variety & Error Guide #3: How to Spot Rare Die Cracks, Double Dies & Mint Mark Fakes on 1916-D Mercury Dime and 1937-D 3-Legged Buffalo Nickel – Most folks glance right past the tiny details that transform a pocket-change coin into a rarity worth thousands. As a li…
• The Hidden History Behind the 1926 Sesquicentennial Commemorative Coins: A Historian’s Deep Dive Into Art Deco, Coolidge, and the Birth of a Nation’s 150th Anniversary – Every relic tells a story. To truly understand the 1926 Sesquicentennial coins, I have to take you back to the era that …
• The Hidden History Behind the 1916-D Mercury Dime and 1937-D 3-Legged Buffalo Nickel: A Historian’s Deep Dive Into Two Controversial Relics – Every relic tells a story. To understand these pieces, I have to look at the era that forged them. As a historian who ha…