How much does light wiping and/or cleaning detract from the value of silver coins?

Bill F. asks: How much does light wiping and/or light cleaning detract from the value of silver coins? How do you identify this?

Disturbing the surface of a coin by cleaning is obvious to trained numismatists and knowledgeable collectors. Yes, it reduces the desirability of the coin and therefore the price. There are situations where coins have been conserved by removing dirt and encrustations, especially when the coin has been in the ground or under the ocean. Trained conservators know how to remove foreign material without further damaging the coin.

Light cleaning or wiping uncirculated coins will downgrade them to AU or lower. That translates, depending on the coin, to 25% to 50% of its “pre-cleaned” value.

When a coin blank is struck by the dies, the metal becomes molten and flows into the recesses of the die and outward from the center to the rim. The metal flow lines are responsible for what we call luster. These lines sit directly on the surface of the coin and are easily removed. Any disturbance of the flow lines by cleaning is immediately detectable by an expert.

Graders look for flow lines first when evaluating an uncirculated coin. Dipping a coin in silver cleaner reduces the height of flow lines because it removes the surface layer of the coin. The first time one does this the coin appears as if it has been improved but along with the toning you’ve also removed the protective oxide layer that develops on all coins. In a short time the coin “needs” to be dipped again. As little as three dippings can be enough to reduce the grade of a coin from uncirculated to AU. Excessive dipping eventually causes a coin to look flat and lifeless since it no longer has any luster.

Even coins with obvious wear normally have luster. Even EF-45 coins will have luster in the protected areas of the coin.

Once the luster is gone from cleaning, the uninitiated usually take to polishing the coin in desperate attempt to restore the coin to uncirculated condition (polishing is the process of moving metal). Polished coins are obvious to anyone accustomed to buying and selling coins. At that point the coin usually has been reduced to its metal value.

Note that wear is not considered damage and is the natural progression of a coin. Though circulated coins are usually less expensive than coins in new condition, they also often have character. There are many collectors that prefer coins in XF and AU grades because of this factor. Also, uncirculated examples of rare dates are often out of the price range of the majority of collectors so nice, untreated, circulated examples are very desirable.