What causes small black specks on gold coins (picture added)?

Longacre

I was looking at a gold coin, and it had what appeared to be black specks on certain parts of the coin. The specks were very small "dots", almost like tiny freckles. Is this just dirt, or is it something else? To my knowledge, the coin has never been cleaned.

nwcs

Those are carbon spots.

Longacre

Are those seen as detracting? Also, are they on the surface of the coin, or within the coin?

nwcs

They are part of the coin itself. Actually, I should probably have said copper spots. If they are small, they usually don't impact the grade much. Big splotchy ones are a negative. They can be a good marker for a genuine coin, too.

coinguy1

Longacre, can you post images of the coin?


<< <i>Are those seen as detracting? Also, are they on the surface of the coin, or within the coin? >>

If it is carbon spots, that IS a detraction. Typically, carbon spots grow on the surface of a coin but can eat into the metal. Gold is less reactive than the other coin metals and carbon spots would be quite unusual.

Copper stains/spots (from the impure alloy), on the other hand, are seen on gold coins much more frequently than carbon spots. The copper spots/stains can vary in hue, from a lighter pink/red color to very dark rust/red - is it possible that you're seeing dark copper stains/spots and not black carbon spots?

Longacre

Here is the spotty coin:

coinguy1

Sorry, I can't tell for certain from the image - it might be carbon or copper spots or even little ticks/hits/depressions on the coin that look like dark spots in the image. If I had to guess, though, I'd go with tiny (remember it's a big maginified image) carbon spots.

mhammerman

Not distracting at all. If you are referring to the spot on her tiara and the couple of spots on the rim, it is not uncommon to see these and the spots speak to the genuineness of the coin. I have seen considerably worse coins with spots going for the full money so this coin probably wouldn't discount much or be penalized at the grading table. The dark spot behind her neck, near the 4 may be something but it may just a photographic goober. Not a bad coin at all, if the money is ok.

MrHalfDime

So-called "carbon spots", a misnomer, can and often do result from impurities landing on the surface of a coin and reacting with the coin metal. This is often due to "spittle", the moisture that sprays, often unseen, from the mouths of talkative collectors while looking at a raw coin. Spittle is quite acidic, as the body produces it to begin the digestive process of breaking down food; good for Big Macs, bad for coins. That is one of the reasons why it is recommended not to talk while inspecting unprotected coins. On a gold coin, the resulting spots are generally due to reaction not with the gold, which is essentially inert, but with the alloyed metal, which is copper in United States gold coins. I often see the copper alloy in gold coins refered to as "impurities", which it is not. It is there intentionally, to produce a coin that will wear longer in circulation than pure gold, which is quite soft.

RYK

The black spots on this coin are dirt: