The shiny appearance of newly minted coins is so beautiful to behold. When a coin leaves the mint after just being struck, it has a beautiful shine or luster that can never be recaptured after the coin enters general circulation or the coin gets cleaned. Either process destroys the original surface characteristics produced as the coin gets struck.
Two of the most asked questions are: “How do I restore the shine to a coin?” and “How can I clean my coins to make them shiny again?” The answer is “You Can’t!”
The shine that newly minted coins have is technically known as “luster.” This mint luster is created during the actual coin striking process, when the coin dies come into contact with the planchet under extreme pressure. The process causes changes to the metal of the planchet at the molecular level. The metal of the planchet is forced by the great striking pressure to flow into the coin dies.
A unique event occurs as a result of this flowing metal being under extremely high pressure. As the metal flows it acquires a beautiful, lustrous shine. This mint luster is a by-product of the coin striking process.
The cause of the coin’s shiny surface appearance stems from what are known as “flow lines.” Flow lines are microscopic patterns in the metal where the molecules have been forced to line up in certain ways. Flow lines are easier to see on large coins rather than on smaller coins.
The light shining off of these flow lines often produces an effect known as the “cartwheel effect.” The cartwheel effect is a term that describes the rotating, windmill like effect of light that mint state coins exhibit. This cartwheel effect is very fragile and disappears as the result of circulation or the coin being cleaned.
To observe the cartwheel effect, hold a newly minted coin with the obverse side up and tilt the coin at various angles to the light. You should see a pattern of rotating lighter versus darker reflection of the light against the coin’s surface as you tilt the coin. With any luck you should have a suitable coin in you pocket change.
The reason we are spending so much effort on describing how the cartwheel effect is produced is because this effect gives an excellent indication of what condition the surface of a given coin is in. It is also a good indication of whether a coin has been cleaned or not.
In today’s competitive coin collecting market, the state or condition of a coin has become a critical element in judging and grading the value of a given coin. If a coin has been determined to have been cleaned its value is significantly reduced.
What we are trying to stress to you in this article is that cleaning your coins is a surefire way to destroy the surface of a coin and conversely destroy the value of your significantly coin at the same time.
The bottom line is that you should NEVER clean your coins. About the only exception to this sacred rule is coins that you find using a metal detector. Even here you want to be extremely careful how you clean the coin, especially if the coin is a rare one.