- You may have seen a variety of letter pairings attached to the grades of some copper coins and wondered what those acronyms mean. These two-letter abbreviations include "RD," "RB," and "BN" and are grading designations that tell something about the surface color of the copper coin to which the grade corresponds. But what do those letters mean, and why are they important to coin collectors?Everything is Science
For decades, coin collectors have pursued copper coins not just on the basis of their numerical or adjectival grade, but also the color of the surface. Copper, after all, is a moderately reactive metal. It begins oxidizing the moment it hits air. When copper coin planchets are new, they have an orangish to orange-reddish hue - one that may appear very bright or warmer in color, depending on the quality of the copper and its composition.
This scientific phenomenon certainly isn't unique to coin planchets. Why, even the copper-skinned Statue of Liberty - the seafoam green monument standing proud in New York Harbor - once appeared dull brown, similar to an aging Lincoln cent. Of course, when the Statue of Liberty was erected in 1886, color photography as we know it today didn't exist, so there are no photos that distinctly show the statue in color during its early years.
But over the course of the 30 years following her completion, the 305-foot-tall monument changed color - no surprise, given the assault of salty sea water, air pollution, wind-driven particulates, and seasonal temperature changes. So, let's pivot this information back to coins.Read the Entire Article