Grading the Color of Copper Coins

How to Tell What Color Your Copper Coins Are

Twenty Copper Lincoln pennies arranged by darkening shades of red to brown.
Copper Lincoln pennies arranged by darkening shades of red to brown. Individual Photos courtesy of Teletrade Coin Auctions, www.teletrade.com; Arranged by James Bucki

In order to properly grade copper coins, you must be able to describe the color of the copper. Over time the brilliant orange/red color of a freshly minted copper coin, such as a Lincoln cent, will diminish and fade to a deep chocolate brown color. As this degradation of color occurs, there are varying degrees in which both red and brown colors will exist simultaneously on the surface of the coin. This color designation only applies to uncirculated copper coins. All circulated copper coins are...MORE assumed to be "brown." This guide will help you accurately describe the color of your uncirculated copper coins.

  • 01 of 06

    The Chemistry of Copper

    Copper Coins of Different Colors
    Grading the Color of Copper Coins. Image Courtesy of: Heritage Auction Galleries, www.ha.com

    Copper is an element with a chemical symbol of "Cu". Compared to other metals, copper is soft, malleable and ideal for the minting of coins since it exists in great abundance. Pure copper has a bright reddish orange color. Unfortunately, copper is also highly reactive to chemicals naturally found in our atmosphere. Oxygen, water vapor, and various acids react with the copper and cause it to tarnish. This oxidation, combined with other chemical reactions, results in its natural bright...MORE reddish orange color to gradually turn into a deep chocolate brown color known as patina.

  • 02 of 06

    Copper Coin Color: Red (RD)

    Copper Cent With Red Color
    Copper Cent Red. Image Courtesy of: Heritage Auction Galleries, Ha.com

    A copper coin when first struck exhibits a lustrous reddish orange color. These specimens are prized by coin collectors and carry a value premium over identical coins that are starting to turn brown. Most coin collectors will agree that if a copper coin has retained about 90% of its original orange-red color it will be designated as "Red" and abbreviated in its grade as "RD".

  • 03 of 06

    Copper Coin Color: Red and Brown (RB)

    Copper Cent With Red Brown Color
    Copper Cent Red Brown. Image Courtesy of: Heritage Auction Galleries, Ha.com

    Once oxidation and chemical reactions start to occur on the surface of the copper coin, its color will start to change from reddish orange to brown. This may include some areas of the coin that are approaching a chocolate brown color while other areas still have some of the original reddish orange color. A common measurement is that between 10% and 90% of the original orange-red color remains. This is termed as a "red brown" coin and is abbreviated as "RB" on coin grading descript...MOREions.

  • 04 of 06

    Copper Coin Color: Brown (BN)

    Copper Cent With Brown Color
    Copper Cent Brown. Image Courtesy of: Heritage Auction Galleries, Ha.com

    When a majority of the coin's surface has reacted with the atmosphere such that the surface of the coin is almost entirely a chocolate brown color, this is considered a "brown" coin and is designated as "BN" on grading descriptions.

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  • 05 of 06

    Copper Coin Color: Green

    Ancient Copper Coin with Green Oxidation
    Ancient Copper Coin with Green Oxidation. Image Courtesy of: Heritage Auction Galleries, www.ha.com

    Many ancient copper coins are recovered from being buried in the ground. The chemicals found in soil react with a copper and cause oxidation that is green in color. On ancient coins this is acceptable and usually noted with the coin's grade. Unfortunately, green oxidation on United States coins is considered damage and renders the coin ungradable.

  • 06 of 06

    Shades of Copper

    Twenty Copper Lincoln pennies arranged by darkening shades of red to brown.
    Copper Lincoln pennies arranged by darkening shades of red to brown. Individual Photos courtesy of Teletrade Coin Auctions, www.teletrade.com; Arranged by James Bucki

    Grading the color of copper coins is very subjective, especially when the color is on the boundary between shades. The chart at the left shows twenty coins representing the various shades of red (R), red and brown (RB), and brown (B). Remember that computer photos do not capture the exact color of the coins, so you may notice some inconsistency from one computer to another.