Gold coin question

Dan50

Being told once that gold never tarnishes, what is the little dark looking areas you see on gold coins? Even worse looking when viewed under magnification? Is this something that can be removed without damage to the coin?

homerunhall

The dark looking spots you sometimes see on U.S. gold coins are copper spots. U.S. gold coins are 90% gold and 10% copper, and the copper sometimes forms spots on the coins.

In most cases the spots will "dip" off, but dipping gold removes the original luster.

Thanks,

David