A capped die strike is caused when a struck coin sticks to the upper die. Once the coin is stuck to the die face, the reverse of the struck coin becomes the new die face. When the next blank is fed into the collar and the strike occurs, the reverse design of the adhered struck coin impresses itself into the new blank. This struck coin is a brockage strike. The coin adhered to the upper die is known as a die cap. It's a spectacular mint error that is very unusual to encounter on an Indian cent.
No Date/Full Brockage/MS64BN
No Date/Full Brockage/VF25
Since the image is raised on the coin adhering to the die, the image on the brockage is incused and reversed - a true mirror image. The first brockage strikes, perfect mirror images and undistorted, are most prized. As additional coins are struck from the capped die, the die cap begins to spread and thin under the pressures of striking, distorting its image. At some point, as the die cap becomes more distorted, the coins struck cease to be brockages and are known as capped die strikes.
While a brockage image is undistorted or relatively so, images on capped die strikes are increasingly malformed. Although the image is recognizable, the design expands, producing an image that can be several times the normal size. Finally, the die cap breaks off or is pounded so thin it ceases to affect succeeding strikes. Sometimes, the die caps fall off early and in a relatively undistorted state. Die caps resemble bottle caps, with the metal wrapping around the surface of the die. Die caps are very rare and collectible, much more so than capped die strikes.