Toning (coin)

Toning on a coin is the change of colour brought about through oxidization, which forms a thin layer of tarnish on the metal's surface, typically as a result of interactions and chemical reactions with sulfur-containing compounds in the environment.

Different colors and patterns of toning can have varying effects on a coin's grade and value.

Toning patterns may cover an entire coin, just one side, or just one area.

Coins which have sat stacked in bags for a long time can develop crescent toning, where the toned coin was partially covered by one sitting off-center on top of it.

This is common with Morgan dollars, which were typically delivered to and stored in banks in large cloth bags.