Black Coin Grading 0

[Mti]

hi

Suppose a coin is of AU quality and grading
But the coin surface is black

 

How are black coin grading ?

 

 

 

Edited April 1, 2020 by Mti

[JKK]

It's tarnish, so it depends on the type of tarnish and how much detail is left. If the coin were actually uncirculated (it happens), tarnish would keep it to one of the lower MS grades. However, if the coin is heavily worn, this sort of tarnish probably isn't a major detractor because the wear is the greater problem. I think that would change if the tarnish rose to the level of serious environmental damage, such as with bronze disease, but when Cu/Ni goes dark this way it's just one of the natural toning paths rather than serious surface erosion.

It can also happen to silver. The coin that set me off on collecting was a worn, completely black Barber dime I found outside my grandparents' ranch house in Kansas. Worn, yes, but not damaged. Of course, there is copper in most minted silver coinage, so the tarnish there is surely a mix of the two. When gold coins tone up, the copper in them can turn to a very interesting series of orange/red touches. My Spanish doubloon has these, very pretty. In gold, I don't think you get much tarnish unless there's another metal mixed in.

As a side note, please stay safe over there, insha'Allah. I know this thing has hit your country hard.

[Mti]

9 hours ago, JKK said:

It's tarnish, so it depends on the type of tarnish and how much detail is left. If the coin were actually uncirculated (it happens), tarnish would keep it to one of the lower MS grades. However, if the coin is heavily worn, this sort of tarnish probably isn't a major detractor because the wear is the greater problem. I think that would change if the tarnish rose to the level of serious environmental damage, such as with bronze disease, but when Cu/Ni goes dark this way it's just one of the natural toning paths rather than serious surface erosion.

It can also happen to silver. The coin that set me off on collecting was a worn, completely black Barber dime I found outside my grandparents' ranch house in Kansas. Worn, yes, but not damaged. Of course, there is copper in most minted silver coinage, so the tarnish there is surely a mix of the two. When gold coins tone up, the copper in them can turn to a very interesting series of orange/red touches. My Spanish doubloon has these, very pretty. In gold, I don't think you get much tarnish unless there's another metal mixed in.

As a side note, please stay safe over there, insha'Allah. I know this thing has hit your country hard.

Thanks for the guide and the note ❀

[Crawtomatic]

I believe with the coin pictured it would get the attribution of Environmental Damage with NGC & PCGS.  If graded by ANACS it would most likely say Corroded.