Here are some of the things you might find on your gold or silver bullion.<\/p>\n
Milk Spots<\/h2>\n
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One of the most recognizable examples is the milk spot.<\/p>\n
Milk spots are irregular white or cloudy-looking marks that can appear on silver bullion, particularly modern silver coins such as the \u9280\u6953\u8449<\/strong>. The Royal Canadian Mint researched the phenomenon and found that multiple factors can contribute, including interactions between silver and contaminants during processing, handling, and storage. Milk spots are not the same as ordinary tarnish or oxidation.<\/p>\n Importantly, milk spots do not change the coin\u2019s fineness or precious metal content<\/strong>. They primarily affect its appearance.<\/p>\n \u5728 2018<\/strong>, the Royal Canadian Mint introduced MINTSHIELD™<\/strong>, a proprietary process designed to significantly reduce the occurrence of milk spots on Silver Maple Leaf bullion coins.<\/p>\n Silver is more chemically reactive than gold, so it can change appearance when exposed to substances in its environment. This is commonly called tarnish<\/strong>, although terms such as toning<\/strong> \u548c patina<\/strong> are also used to describe changes that develop on a metal\u2019s surface.<\/p>\n Silver can gradually develop shades ranging from yellow and grey to brown, blue, purple and black. These changes are often caused by reactions between the metal\u2019s surface and compounds in the surrounding environment.<\/p>\n Not every aged-looking finish is accidental. An antique finish<\/strong> is sometimes intentionally applied to bullion or collectible items to give them a darker, aged or tarnished appearance.<\/p>\n Tarnish and toning generally have little effect on the underlying metal value of bullion. For collectors, however, appearance can matter considerably. Some prefer bright, untarnished surfaces, while others actively seek out coins with attractive toning or patina.<\/p>\n Silver and other precious metal bullion can develop dark spots, patches or other forms of discolouration. These may result from normal tarnishing, environmental exposure, chemicals, contaminants or storage conditions.<\/p>\n One particularly striking form of discolouration on silver coins is rainbow<\/strong> \u6216 oil-spill tarnish<\/strong>. Instead of simply becoming darker, the surface develops shimmering combinations of purple, blue, green, yellow and gold. This happens when a very thin surface layer interacts with light, resting different colours depending on the layer\u2019s thickness and viewing angle.<\/p>\n Rainbow-toned silver is not necessarily considered undesirable. Some collectors actively seek out colourful or unusual toning, and particularly attractive examples can command a premium.<\/p>\n Reddish or orange spots can sometimes appear on precious metals and are commonly referred to as copper spots<\/strong>.<\/p>\n This can be surprising on gold bullion, particularly when the item is stamped 99.99%. But these spots do not necessarily mean there is a significant amount of copper in the bullion.<\/p>\n No gold bullion is technically 100% pure. The highest fineness produced is 99.999%, meaning there is still a very small fraction of other elements present.<\/p>\n Bullion can also be manufactured in facilities where other metals, including copper, are worked with. Trace amounts can potentially become incorporated into the metal or its surface during production. Over time, these traces can react with the environment and become visible as reddish or orange spots.<\/p>\n Copper spots can therefore appear even on 99.99%<\/strong> \u548c 99.999%<\/strong> gold bullion. Their presence does not automatically mean that a piece is counterfeit or that its stated fineness is incorrect.<\/p>\n For bullion, copper spotting does not change the underlying precious metal value. However, prominent spots can affect the premium on a collectible or numismatic item because appearance and condition matter to collectors.<\/p>\n Green discolouration is most commonly associated with verdigris, a term generally used for green corrosion that develops on copper and copper-containing metals.<\/p>\n This can become relevant to coins and bullion because some products contain small amounts of copper or other metals, and because the materials used to store them can affect their surfaces.<\/p>\n Certain plastics, particularly PVC-containing materials<\/strong>, can release chemicals as they deteriorate. These chemicals can react with coins and other metal objects, potentially creating sticky green deposits, discolouration or corrosion.<\/p>\n This is one reason collectors take care when choosing coin holders, flips and other storage materials. If you find a green or sticky substance on your bullion, avoid scrubbing or cleaning it yourself. Improper cleaning can damage the surface and potentially affect collector value.<\/p>\n Bullion is primarily valued according to its precious metal content – including its weight and fineness – and the current market price of the metal.<\/p>\n A milk spot doesn\u2019t remove the silver from a Silver Maple Leaf. Tarnish doesn\u2019t remove the silver from a silver coin. A copper spot doesn\u2019t mean the gold has suddenly become less pure.<\/p>\n However, appearance can matter when an item has additional numismatic<\/strong> \u6216 collector value<\/strong>. Collectors may pay premiums for rarity, condition, attractive toning or special finishes. Conversely, undesirable spotting or surface damage can reduce the premium someone is willing to pay.<\/p>\n If you discover a strange mark on your bullion, your first instinct might be to clean it. That can be a mistake.<\/p>\n Polishing, abrasives and chemicals can permanently alter a coin\u2019s surface. On collectible pieces, cleaning can potentially do more harm to the item\u2019s value than the original spot or tarnish.<\/p>\nTarnish, Toning and Patina<\/h2>\n
![\"\"](\"https:\/\/abbotsfordgold.ca\/wp-content\/uploads\/2026\/11\/tarnish-patina-johnson-matthey-silver-bars-1024x576.jpg\")
<\/p>\nDark Spots and Discolouration<\/h2>\n
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<\/p>\nCopper Spots<\/h2>\n
![\"\"](\"https:\/\/abbotsfordgold.ca\/wp-content\/uploads\/2026\/11\/copper-spot-gold-johnson-matthey-bars-1024x640.jpg\")
<\/p>\nGreen Spots and Verdigris<\/h2>\n
![\"\"](\"https:\/\/abbotsfordgold.ca\/wp-content\/uploads\/2026\/11\/green-spots-verdigris-old-coins-1024x576.jpg\")
<\/p>\nMetal Value vs. Collector Value<\/h2>\n
Think Twice Before Cleaning Your Bullion<\/h2>\n
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