The Truth About Cleaning Coins
One of the most common mistakes new collectors make is cleaning coins in an attempt to make them look better or “shinier.” While that instinct makes sense—after all, who doesn’t like a bright, clean coin?—in numismatics, cleaning is one of the fastest ways to destroy a coin’s value.
Here’s why you should almost never clean a coin, how experts can tell when one has been cleaned, and what to do instead.
1. Cleaning Changes the Surface
Every coin, even circulated ones, has a unique surface texture formed by the minting process and years of aging. When you clean a coin using chemicals, polish, or even a soft cloth, you’re actually removing layers of metal from that surface.
The result? Microscopic scratches, dull patches, or unnatural shine that make the coin instantly recognizable as altered.
To an expert, a “cleaned” coin doesn’t look new—it looks damaged.
2. Collectors Value Originality
Numismatics is about authenticity and preservation, not appearance. A coin with natural toning or light dirt is more desirable than one that has been stripped of its original surface.
Collectors and grading services value originality so much that:
PCGS and NGC will label a coin as “Cleaned” if they detect it.
Such coins often sell for 50% to 90% less than their uncleaned counterparts.
Even gentle “rinsing” can be enough to change the surface’s reflectivity, especially on proof or mint state coins.
3. Grading Services Can Always Tell
You can’t fool the pros.
Trained graders look for:
Hairline scratches from wiping or brushing.
Unnatural brightness or “cartwheel” luster distortion.
Residue patterns from dips or chemicals.
Even if the coin looks perfect to the naked eye, a grader with magnification and experience can spot these clues instantly.
4. Exceptions: Safe Conservation
There are safe ways to remove dirt or contaminants — but they should only be done by professionals.
NGC’s “Numismatic Conservation Services” (NCS), for example, specializes in conserving coins — meaning they carefully remove contaminants without altering the metal surface.
If you find a rare coin with sticky residue, tape, or PVC damage, professional conservation might save it — but DIY cleaning almost never does.
5. What You Should Do Instead
Leave it alone: Natural patina is part of a coin’s story.
Store it properly: Use acid-free holders and avoid humidity to prevent further toning.
Handle with care: Always hold coins by the edges.
If unsure, ask a dealer: A trusted coin shop can advise whether conservation is worth the cost.
Final Thoughts
Cleaning a coin may seem like harmless maintenance, but in the numismatic world, it’s permanent damage. What you think improves a coin’s appearance actually erases history—and value—forever.
Keep your coins original, and they’ll be worth far more in the long run.
For more collecting tips and storage guides, visit CoinCollectingTools.com.