Why Cleaning Coins Reduces Value
Cleaning coins might seem like a good idea to make them shine, but it can drastically reduce their value. Why? Cleaning can strip away the natural toning and mint luster that contribute to a coin’s authenticity and market value. Signs of cleaning, like hairline scratches or unnatural brightness, often result in lower grades from services like NGC or PCGS. In many cases, it’s better to leave coins as-is or consult a professional appraiser.
Who are PCGS and NGC
PCGS (Professional Coin Grading Service): Founded in 1986, PCGS is a top U.S.-based third-party service that authenticates, grades (Poor-1 to Mint State-70), and encapsulates coins in protective “slabs.” It assesses condition based on wear, luster, strikes, and eye appeal, offering trusted certification that influences market values and guards against fakes.
NGC (Numismatic Guaranty Corporation): Established in 1987, NGC is a leading U.S. grading firm for coins, tokens, and medals. It uses a similar 70-point scale, encapsulates for preservation, and provides variety attributions. Known for research and global focus, especially on ancient and world coins.
Both provide objective condition evaluations through expert exams, noting authenticity, preservation, and alterations like cleaning. This enhances market liquidity for buying, selling, and insuring coins, though fees apply and grades may vary slightly due to subjectivity.
Signs of Cleaned Coins
Signs of cleaning include microscopic scratches or hairline marks from abrasive methods, visible under magnification. The color might be “off”—too bright or unnatural. Breakups in natural luster, flat details, or incuse parallel lines when rotating the coin are red flags. For silver coins, check for unusual rust spots or discoloration post-dipping.
Reasons to Avoid Cleaning
Avoid cleaning because it destroys the coin’s original surface, making it a “problem” in grading terms, often leading to lower values or rejection by services like NGC or PCGS. Collectors prize natural toning; cleaned coins lose this authenticity.
Among the most common reasons for a coin to receive Details Grading is unskilled and improper cleaning. The temptation to “improve” a coin’s appearance by chemically or mechanically cleaning it seems acceptable, until the possible detrimental effects are later explained to the collector. Light, non-destructive cleaning, particularly when found on older coins, may still permit numeric grading. Harsher cleaning that is destructive to a coin’s aesthetic appeal, however, will result in Details Grading only, and such cleaning is not correctable with conservation.
BRUSHED describes a coin that has been wiped with an abrasive brush. The affected areas may be narrowed down to OBV BRUSHED or REV BRUSHED.
BURNISHED is the term used when the cleaning is more aggressive and gives the coin a very brilliant but unnatural sheen. Sometimes this action is performed with some abrasive media such as ball bearings, or it may result from treatment within a rock tumbler.
IMPROPERLY CLEANED is a generic term to describe unskilled cleaning when the exact nature of the action is uncertain.
POLISHED is similar to BURNISHED, though it’s typically applied when the abrasive action is less severe.
SPOT REMOVALS describes the unskilled, mechanical removal of “flyspecks,” small black spots of intense toning or corrosion. It also refers to similar removal of reddish “copper spots” often seen on gold coins.
WHIZZED coins have been cleaned with a fast, rotary wire brush in order to simulate the effect of mint luster on a circulated coin. These are easily spotted by experts, as their lettering and other design details typically are distorted a bit by this action.
WIPED describes a coin that displays surface hairlines in one or more isolated areas. This is usually the result of accidental mishandling rather than intentional cleaning, but it still requires Details Grading. NGC’s graders may specify OBV WIPED or REV WIPED to more accurately describe the condition.
Reference: NGC Details Grading
What to Do If You Suspect Cleaning
If you suspect cleaning, consult a professional appraiser rather than attempting to fix yourself.
Get Expert Help from PGS Gold & Coin – At PGS Gold & Coin, we offer free in-store evaluations to help you understand what your coin could be worth – before you commit to the time and cost of professional certification.
Why Choose PGS Gold & Coin?
- Trusted by families across Chicago and the surrounding suburbs since 2008
- Certified, knowledgeable appraisers on staff
- Transparent pricing with no hidden fees
- Multiple locations and a discreet, welcoming environment
- Optional on-site estate consultations for large or complex collections
We’ve earned the trust of thousands of people across Chicago and the surrounding suburbs for over 17 years, offering a professional, friendly experience from start to finish.
📍 Visit a nearby location or get started online at staging.pgsgoldandcoin.com