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  2. Coin cleaning - Wikipedia

    en.wikipedia.org/wiki/Coin_cleaning

    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

  3. Toning (coin) - Wikipedia

    en.wikipedia.org/wiki/Toning_(coin)

    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.

  4. Gold coin - Wikipedia

    en.wikipedia.org/wiki/Gold_coin

    Gold coins for sale at the Dubai Gold Souk. A gold coin is a coin that is made mostly or entirely of gold.Most gold coins minted since 1800 are 90–92% gold (22‑karat), while most of today's gold bullion coins are pure gold, such as the Britannia, Canadian Maple Leaf, and American Buffalo.

  5. Couple finds gold in their tap water in Whitehall, Montana

    www.aol.com/news/2014-06-06-couple-finds-gold-in...

    Brown's neighbor is also seeing gold in his tap water, and while finding one of the most precious metals on earth might seem exciting, it's actually raising serious questions about the town's ...

  6. Gold plating - Wikipedia

    en.wikipedia.org/wiki/Gold_plating

    Gold plated - gold layer thickness greater than or equal to 0.5 micron; Heavy gold plated / Vermeil - gold layer thickness greater than or equal to 2.5 micron; Gold plated silver jewellery can still tarnish as the silver atoms diffuse into the gold layer, causing slow gradual fading of its color and eventually causing tarnishing of the surface ...

  7. Why Costco is selling gold bars and silver coins

    www.aol.com/why-costco-selling-gold-bars...

    The coins are non-refundable, and members can purchase a maximum of five. Costco is trying to replicate its recent success with gold bars. It began selling $2,000 gold bars online in September and ...

  8. Why do we toss coins into fountains? - AOL

    www.aol.com/why-toss-coins-fountains-160126436.html

    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 ...

  9. Tarnish - Wikipedia

    en.wikipedia.org/wiki/Tarnish

    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 ...