Question if I may ask

MattandKim

I am waiting for my books and such to come in but I do have 1 question not to bother anyone... but why would some coins have a rainbow look to them... I know grease can get in the process on making the coins but I'm not sure what it all looks like.. have several with rainbow looking colors and some with black

JBK

Toning. Tarnish. Heat. It's all part of the oxidation process.

JBK

Also, I am not sure where you are getting your coins to search through, but the more you look at the more stuff you will see. If you can get a $50 box of cents at the bank (as long as they aren't all new) you will see all sorts of weird and unusual stuff. I have learned a lot by roll/box searching.

ricko

Silver coins tarnish with heat, humidity and environmental contamination.... Copper too..... Many collectors pay a premium for attractive tarnish color.. They call it 'tone' or 'toning'... It is tarnish, which does not sound as attractive. It is, fundamentally, environmental damage to the coin surface. Cheers, RickO

jmlanzaf

A picture would be helpful.

Oil is not rainbow colored. What makes you see the rainbow colors on an oily puddle is an optical interference phenomenon known as the thin film effect. Any material can cause this, including surface oxidation (toning) of coins. As the layer gets thicker, the effect disappears and you end up with the true color of the compound. That's why oil is brown in a glass but shows a rainbow of you throw a little in a bowl of water. If you throw a lot in a bowl of water, you see a clear water layer, a brown oil layer, and no rainbow.

Jzyskowski1

Those toned coins can be very valuable. Like 5x of regular price. Many collect them so handle carefully. ( there’s very strong feelings around here about toning versus tarnish and for fun ask about natural toning versus artificial toning. 😂
I buy what I like and don’t care if it’s AT or NT. However, I’m pretty much alone, in that most have a fixed opinion 😉

gumby1234

Spectacular looking toned coins can command huge premiums over their untoned or ugly toned coins. Here is one of mine.