Everything One Needs To Know About Toning

(per coin chemistry)

Toning is the conversion of the surface Ag atoms to Silver Sulphide (Ag2S).

If the layer is less than about 50nm (nanometers) it's not visible to the human eye. More than about 150nm it appears black. So the pretty colors represent a spectrum from 50nm (yellow) to 150nm (dark blue).

For reference a human hair is typically 90 microns or 90,000 nm.

The atomic radius of Ag is 165pm (picometers) or 0.165 nanometers.

about 300 atoms converted = yellow
about 900 atoms converted = black

Prove it... that's the rub. How do you prove it was intentional exposure instead of years of incidental exposure.

But since it is exactly the same chemically (and I don't see differences in the 2 responses) that's why a purist doesn't differentiate between pretty and damaged.

Pretty sells for more and IMNSHO is why TPG doesn't downgrade...

Plus - and this is really shaky chemistry, it's been 30 years and I wasn't THAT good to begin with - there is a difference in the compound size, so there IS metal movement.

2 Ag atoms have a bond length of 288.9nm, so the Ag2 (Ag = Ag) molecule is 160nm x 608.9nm.

The S bond length is 205nm, plus 100nm for the atom itself, and there are two bonds (Ag - S - Ag). I believe it bends, so it's not straight, but straight would be 160nm x 830nm or each silver atom moves 110nm.

Can you see it? No - the limit of the human eye is half a hair or 45,000 nm. But if you remove that 150nm of coating, is it really the same surface that came from the mint?

If I scrape off 1 layer of skin, do you notice? Probably not as it doesn't cause pain. Scrape off 50 layers of skin and your nerves will scream bloody murder.

Bstrauss by the two different explanation comments I just meant you broke it Dow chemically and the other response was more in leymans terms combining the two gave me a full understanding! It was just a comment to both of you :)