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These coins are graded with a description which lowers the coin's value by 90%. [14] [16] Dipping: The coin is dipped into a dilute acid solution that removes the oxidation from the coin along with a small amount of metal. Overdipped coins result in loss of luster which lowers the coin's grade and appeal. [12] [9] Ivory soap and Water
Bronze disease is an irreversible and nearly inexorable corrosion process that occurs when chlorides come into contact with bronze or other copper-bearing alloys. [1] It can occur as both a dark green coating, or as a much lighter whitish fuzzy or furry green coating. [1]
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.
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Colored dye or smudges can affect the perceived color of a gem. [citation needed] Historically, some jewelers' diamonds were mis-graded due to smudges on the girdle, or dye on the culet. [citation needed] Current practice is to thoroughly clean a gem before grading its color as well as clarity. [citation needed]
Tarnish does not always result from the sole effects of oxygen in the air. For example, silver needs hydrogen sulfide to tarnish, although it may tarnish with oxygen over time. It often appears as a dull, gray or black film or coating over metal. Tarnish is a surface phenomenon that is self-limiting, unlike rust. Only the top few layers of the ...
The quality of all coins is not equal and collectors felt the necessity of defining the quality of the coins in order to assess their value. Rim damage, nicks, polishing, cleaning, scratches and other forms of wear are considered factors in grading a coin. Whether or not a coin shows evidence of having been mounted in jewelry also affects its ...
Where the money goes. Some well-known fountains can collect thousands of dollars in coins each year. According to an NBC report from 2016, the Trevi Fountain accumulated about $1.5 million in ...