No Date Visible - Determining 92.5% From 80% Silver George V Coins?

It makes it so much easier when you find a Edwards or Victorian in the junk pile.

I found a Victorian one last week but couldn't see the date so I passed though I hate myself for it.

I found a Edwards with a worn date of 1907 for the 80% price last week. They look so similar to the George V quarters. Super fortunate the portrait is mirror flipped. It was so worn though I can't believe the date stayed on it partially.

I never heard of anybody selling silver coins at face but if I do I'll be first in line.

I've heard of lucky people buying silver at face value from banks, who for some reason had the coins separated and the tellers didn't 'buy' the coins for face value themselves.

On this website you can type in an estimate of how much wear % you think the coin has (if it's not in-hand) and get a good estimate that way.
http://coinapps.com/silver/coin/can.../calculator/
But of course if you can, always weigh it yourself.

I have a very precise scale - 300g accurate to 0.001g, and after some testing I've found an average circulated coin (VF) can loose 4-8% and a very worn out coin (AG or worse) can be as high as 12-15%

If it's worn so badly you can't tell the date, an acid spot is not a big deal, as it has no collector value.
But yes I'd like to try that too, maybe a very large neodymium magnet.

Now that I think about it...
The composition is 92.5% Silver, 7.5% copper
And 80% Silver, 20% Copper
Copper is very weakly magnetic - think of the 'magnetic' vs. 'Non magnetic' varieties in modern Canadian pennies

Referring to the coin specification website I posted above:
The magnetic ones are made mainly from Steel - 94% Steel, 4.5% Copper, 1.5% Nickel 2002-2012)
The non- magnetic variety is 98.4% Zinc, 1.6% Copper. (1997-2012)
And for simplicity's sake anything 1858-1996 is 95-98% Copper, and a small amount of tin and zinc. Which is non-magnetic as well.


I'm still going to try testing the silver alloys with the strongest magnet I can find for the heck of it, but I expect it would be impossible to tell without high-end expensive lab grade magnetic fields.

My first reply simply points out that Yes there is a way..if..you really..need to..know.

Otherwise the truth of the matter is..


IMHO

Argh, that app is called CoinTrust and they want $13.99 for it. Nope :P
I love the idea though! They use frequency plots of what sounds the coin makes as it spins/rattles/settles on a hard surface. And compare that to a known frequency response.



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It would be worth trying the tissue paper test; perhaps the 80% silver might appear a little darker behind the tissue. The ring test sounds like a neat idea to try, but I would be afraid that coin geometry might confound the test too much; it is possible that the ring depends more on the level of wear than the composition.

For the magnet test, it's not an issue of para/diamagnetism. Both copper and silver are weakly diamagnetic, and this effect would be exceedingly difficult to test, without a water bath or extremely sensitive scale. What I was thinking is to drop the coin down a chute of sorts so it passes in close proximity to a very large and strong NdFeB magnet. If it is sterling silver, it should slow down more than if it is 80%, since the alloying with copper should decrease electric conductivity and subsequent eddy currents when passing through the magnetic field.

If you have a big magnet and can figure out a timing rig or sensitive way to separate the two based on how the magnet slows the coin, this would be my first go at separating them non-destructively.