A term used to describe the colour of dark spots found on the surface of a coin. The spots do not normally comprise the chemical 'carbon' and are more commonly found on bronze coins.
Diamonds are 99.95% pure carbon; but 25 other different mineral inclusions or small crystals, have been found within diamond as well. These are not carbon spots, but rather small crystals that were trapped within the host diamond as it was forming in nature. Sometimes, they just happen to be dark in color. The most common mineral found within diamond is diamond.
An internal imperfection in a gem that looks black or gray.
A misnomer. As diamonds are composed almost entirely of carbon, any black spots in them are unlikely to be carbon.
Spot, mainly on copper and gold coins. Carbon spots are brown to black spots caused by oxidation.
a brown to black spot of oxidation on the surface of a coin
A small spot of corrosion or oxidation on a coin caused by contamination.
A dark discoloration on the surface of a coin. It is possible that this discoloration is caused by a planchet imperfection prior to striking, or it may be caused by improper storage of the coin. Regardless of the cause, carbon spots are difficult, if not impossible, to remove without leaving pits in the coin's surface. If they are large enough, they can significantly lower the grade and value of a coin.
A spot seen mainly on copper and gold coins, though also occasionally found on U.S. nickel coins (which are 75 percent copper) and silver coins (which are 10 percent copper). Carbon spots are brown to black spots of oxidation that range from minor to severe – some so large and far advanced that the coin is not graded because of environmental damage. See Also -- copper spot
