The the black marks on my gold coin diminish its value?

JMT356

I purchased a 1-oz. Austrian Gold Philharmonic coin. When it arrived, I noticed a black mark on the “O” and the “R” in the word “Philharmoniker” and on the cello on the back of the coin. Please see the attached photo.

What are these marks? Are they cooper spots? Will they impact or diminish the grade and/or value of the coin?

JBK

Copper spots, I assume.

As bullion, impact to grade should not be an issue.

Oldhoopster

The spots won't affect the bullion value, but they do make it less desirable to someone who wants to add an example to a collection, IMO

7Jaguars

Have you tried the usual? Acetone, dip, electrolysis (look it up) with the aluminum foil and baking soda. It is difficult to make out just exactly what the spot is, but if it is alloy/copper oxidation it may respond to the later methods.