George V, 1 Rupee, 1918 (Bombay mint)

[Overlord]

Not in great shape, but the only one I have...

[Rangnath]

It is a fine looking coin.  What do you think the dark spots are? 
richie

[Overlord]

What do you think the dark spots are? 
richie

The tiny black spots may be moisture spots, caused by a careless person coughing or breathing on the coin. Moisture condensation may also occur if coins are moved from a cold place to a warmer one.

[Rangnath]

I wonder what one could use to remove them?  Couph medicine?
I guess I'd be inclined to try to clean them.. distilled water, mild detergent, soft brush.. that kind of thing, and then if that didn't work, I'd try ACETONE. 
Or,
I'd ask Bruce
at this site on: Cleaning, Conservation, and Storage.

Bruce Knows.

Of course, maybe he knows that you can't remove black spots, but I'd try. 
richie

[Overlord]

I wonder what one could use to remove them?  Couph medicine?
I guess I'd be inclined to try to clean them.. distilled water, mild detergent, soft brush.. that kind of thing, and then if that didn't work, I'd try ACETONE. 
Or,
I'd ask Bruce
at this site on: Cleaning, Conservation, and Storage.

Bruce Knows.

Of course, maybe he knows that you can't remove black spots, but I'd try. 
richie

Thanks for the tips, Richie. I prefer to leave my coins as I find them. With my skills, any sort of cleaning operation is likely to do more harm than good.

[Rangnath]

That sounds like a good strategy to me.
richie

[Figleaf]

The black spots look like silver oxyde to me. My recipe would be to dilute some lemon juice with water, dab the spots with the solution and work at them with a wooden toothpick. Don't forget to neutralize afterwards (rinse with clean water and dry). If that doesn't work, add more lemon juice to the solution. Bruce may have a better solution.

Peter