Grading copper coins can be one of the most difficult tasks a coin collector can encounter. One of the factors that are taken into consideration when grading copper coins (for example, Lincoln pennies) is the color of the copper. As copper comes in contact with air, water vapor and other chemicals the copper will turn from a bright orange-red to a dark chocolate-brown. Grading companies assign the following adjectives to uncirculated copper coins: Red, Red Brown, and Brown. In my guide to grading the color of copper coins I have added a chart showing twenty different Lincoln pennies and their associated "color grade." These are actual examples that have been graded by a professional grading service. You can use this chart to determine the shade of copper for your coins.
Individual photos courtesy of Teletrade Coin Auctions, www.teletrade.com