Most, however, of the situations discussed below describe faults that coins show in reaction to the stresses of burial in the earth and handling by people both ancient and modern. It is quite possible that these factors could continue to change with time. Careful cleaning can greatly improve the appearance of some coins. Amateur efforts at cleaning can reduce the value of a coin substantially. Brightly cleaned surfaces can retone attractively but corrosion can eat away coins stored improperly.
Coins are hard to improve and easy to ruin while in the hands of modern collectors.
VF Rainbow toning Septimius Severus Victory rx. Rome mint denarius Silver coins also can take on a multicolored hue. This also can be chemically induced. Patinas can be found in a range of colors. Green is common and popular.