Why You Should Never Clean Your Coins Before a Professional Appraisal
When people uncover old coins—whether from a shoebox, an inherited estate, or a metal detector find—the instinct to “make them shine” is natural. However, cleaning coins can dramatically lower their value and, in most cases, cause irreversible damage.
At Keywell Collectibles, we’ve seen countless potentially valuable coins lose hundreds or thousands of dollars due to improper cleaning. You should never clean your coins before getting them professionally inspected.
🧪 Cleaning Destroys the Coin’s Surface
Coins develop a natural patina over time—an aging layer formed due to oxidation. This surface tells a story of a coin’s history and can help numismatists identify its origin, authenticity, and condition.
When you clean a coin, you risk:
- Scratching the surface, even with soft cloths or cotton swabs
- Removing toning, which many collectors pay a premium for
- Exposing micro-damage, which can disqualify coins from certain grading tiers
According to the Professional Coin Grading Service (PCGS), cleaned coins often receive a “Details” grade—a significantly lower designation than if left in original condition. This label can reduce a coin’s value by 30–90%, depending on the coin type and rarity.
💸 Devaluation Happens Instantly
In the world of coin collecting, originality is everything. Even coins with visible grime, toning, or discoloration are often more desirable than the same coin that’s been polished or dipped.
A 1916-D Mercury Dime in XF (Extremely Fine) condition can command $1,000 or more—but if it’s been cleaned, the same coin may sell for less than $400, depending on the buyer’s trust in its integrity.
A similar drop has been seen in early American large cents, where over-cleaning can erase intricate die marks or environmental characteristics that specialists use for authentication.
🧠 Let the Experts Evaluate First
Instead of taking matters into your own hands, the best first step is to:
- Store coins properly (in original holders, flips, or archival-safe containers)
- Avoid touching the face of the coin—hold by the edges
- Bring them in for a professional, no-obligation evaluation
At Keywell Collectibles, we offer free overviews for small groups of coins and detailed appraisals for larger collections. We can also recommend safe preservation methods that maintain value without harming your coins.
🏁 Conclusion: Original Surfaces = Original Value
Cleaning coins may seem helpful, but it’s one of the biggest mistakes collectors can make in the world of numismatics. By letting a professional appraiser examine your coins first, you’re protecting their appearance, potential legacy, and financial worth.
Got a collection you’re not sure how to handle? Contact Keywell Collectibles today and protect your coins the right way.
