When Should You Polish a Coin

The short answer is that under no circumstances should you ever polish a coin. Coins develop a "patina", a natural oxidized coating that preserves the metal underneath and creates a pleasing appearance. Polishing a coin removes that patina, creates an unnatural color and surface wear and speeds the deterioration of the coin. Some coins, such as steel Lincoln pennies from World War II will completely rust through without the protective zinc coating originally applied to the coin. Dealers may have to reapply zinc before they can even sell such coins. For a true coin lover, the destruction of beautiful pieces by the ham-handed is a continuing horror. I have had coin dealers confide their private dismay at the proud coin polisher who had just removed thousands of dollars with each stroke of his hand.

Old coins are not dirty. They do not need to shine. Each type of coin develops a unique patina through age and chemical action that helps authenticate the piece. Amateurs believe that they can improve the appearance of the coin with a little judicious tidying up, but the unpolished coin is as good as it gets. Each coin has a grading standard that establishes grades from poor to brilliant uncirculated. The level of detail visible determines the value of the coin, brightness has nothing to do with it and in the extreme can render a coin unsaleable at any price.

Coin grading can be so subtle that there are multiple grades of uncirculated and proof that account for how fully struck the coin is. A more well-struck coin will show a greater level of detail. The best possible condition is a frosted proof struck from new dies reserved to create coins for display. A few strikes later and the same dies will still provide a beautifully struck presentation piece, but the frosting will be gone. The exact color of the coin surface may be described, especially for uncirculated pieces struck from standard dies, ie. MS 65, with blue surface (MS stands for "mint state") An MS 65 coin is a well-struck uncirculated coin, but it does not meet the highest, deepest standards for which MS 70 is reserved. These grades were derived from an early book by an author named Shelton that was originally used to grade American large cents. For most coins the lowest collectible grade is fine, although good is acceptable for extreme rarities.

Typical grading points can be as subtle as the number of feathers on the eagle's breast on the reverse of a Morgan silver dollar or the wheat grains on the reverse of a Lincoln penny. These subtle details can be removed entirely through the use of acids and abrasive polishes. Furthermore, professional jeweler pastes contain cyanide and can easily lead to the death or injury of an uninformed person. Any but the most neophyte collector instantly spots the polished or "whizzed" coin because surface details are missing, color is wrong and dirt is lodged in the deepest crevices of the piece.

The best cleaning is a little soap and water to remove surface dirt while preserving the patina. If you want to spend the dough, you can invest in an ultrasonic cleaner that will gently vibrate the dirt out of the piece. Your best investment however, is a good library that includes several grading and pricing guides, a magnifying glass, some coin tongs so that you don't damage your existing pieces with friction from handling or acid from your body. Another excellent investment is specially made coin holders that can be folded over and stapled to display the coin and protect it from the elements. Good luck and happy hunting.