Do you have the knowledge and skill to determine whether or not a coin has been cleaned? If not, be safe and follow these basic guidelines before making your next purchase.
The first step in identifying whether or not a coin has been cleaned is to look for unnatural bright surfaces. This is a cue that the surface may have been scrubbed. New coins have a natural luster or brightness, but as a coin wears this brightness starts to fade. By the time a coin reaches the grade of Very Fine the luster may have disappeared.
Any coin that is below the grade of About Uncirculated and appears to have full luster should approach with caution. There is a strong possibility the coin has been polished. Coins in Uncirculated condition are more difficult to detect because brightness is expected in those grades. Over time you will acquire the ability to determine what real and original luster looks like, thus reducing your chances of being fooled by a cleaned coin.
Until you gain the skill and knowledge to be able to identify a cleaned coin, it is recommended you stay with certified coins. These are coins that have been certified, graduated, and authenticated by a third-party grading service. Grading services that are reputable will typically not certify a coin that is cleaned unless they make a notation on the holder label. By sticking with certified coins it will remove any doubt and allow you to focus on the important part, buying quality coins!
So now you're probably wondering about a few of the methods used to clean coins? A variety of techniques can be used including being dipped, scrubbed, or erased.
Dipped coins have an enhanced appearance after they have been "dipped" in a chemical cleaner. Usually this is done with silver coins to remove toning. If done correctly, dipping can improve the appearance of a coin and may be difficult to detect.
Scrubbed coins are the result of "scrubbing" coins with a rough abrasive. Look for hairline scratches, lack of luster, or bright polished surfaces. This devalues coins are significant and should be avoided unless it's a true rarity.
Erased coins are the result of someone using an eraser on a pencil to remove spots or toning. This causes localized areas of fine scratches due to the abrasives embedded in the eraser. It's possible to see these scratches if you put the coin under a light source and turn the coin to just the right angle.
The majority of coins are perfectly safe and have not been tampered with or cleaned. With that being said, it never hurts to have the knowledge necessary to avoid the ones that have. Be safe and use this information to help guide you through your next coin buying experience.