The process of minting coins involves striking metal blanks with dies that imprint the coin’s design. A die is a hardened metal stamp used to impress a design onto a softer metal surface. In a properly functioning minting process, the obverse and reverse dies are aligned so that the front and back designs of the coin are oriented correctly relative to each other.
Die Rotation
Die rotation errors occur when one or both of the dies used in the minting process are not fixed correctly in the coining press, causing them to rotate from their intended position. This misalignment can happen due to several reasons, including improper installation, mechanical failures in the coining press, or wear and tear on the machinery that allows the die to shift during operation.
Die rotation can manifest in various ways, depending on the degree and direction of the rotation. The severity and collectibility of a die rotation error are often judged by the angle of rotation, which can range from a few degrees to a full 180 degrees (known as “coin rotation” or “medal rotation”). Here are some common scenarios:
Minor Die Rotation: A slight rotation, often less than 15 degrees, may not be immediately noticeable to the untrained eye. These errors are relatively common and may not significantly impact the coin’s value.
Significant Die Rotation: Rotations between 15 and 90 degrees are more noticeable and uncommon. Coins with these errors are sought after by collectors due to their rarity and the evident mistake in alignment.
Full 180 Degree Rotation: This is when the reverse die is rotated a full 180 degrees relative to the obverse die, resulting in the front and back designs being upside down relative to each other. These errors are rare and highly prized.
Multiple Rotations: In very rare cases, a die might rotate multiple times during a coin’s production run, leading to variations in rotation errors across the same issue of coins.