Hi, Have you ever seen purplish-bluish spots on silver coins? Particularly, Maple Leaf coins? It looks like that blue-violet-purple rainbow effect that you get when heating some metal. I saw it on the edges of some coins (the reeded edge). (I don't know how coins can get this rainbowish tone or whether if it can go away) What is this?
I presume they are silver coins from your description. This is tarnish and normal with handled coins exposed to air. Not handling the coins, being in airtight tubes and with silica gel packs will delay this process or tarnishing. You can get some tarnish removal products. I have never used any so cannot comment if they work. As you never said if your coins are silver or gold, if they are gold you should get them tested . Some gold coins do have small red/rust spots with die to isolated dust or external partial in the mint process, I think.
They're silver coins, 1 oz Maple Leaf. It's the first time I notice something like this. It's on the reeded edge around. The coin is in a tight plastic pocket (not airtite capsule, so there is some air going circulating in and out). The tone is a bit like this (purplish-bluish): http://www.silvercoins.com/wp-content/uploads/2014/12/silver-dollar-toned.jpg Only that the hazy rainbow spots are more towards purple-violet-blue. No red/orange.
