brian0918 wrote:So assuming that they make them to the correct dimensions, which should be easy, the weight would more difficult to get right, so a very accurate scale would be the most important investment.
What other tests are there? Would an acid test work work if it's silver plated? How about a sound test?
I generally don't bother with calipers on silver coins/rounds/bars, just weight, on gold I feel its more important as mistakes are significantly more expensive...
Acid test is destructive, but would work, you would have to first scratch the coin with a knife, then test the scratch, I do it on silverware/sterling teasets/hollowware all the time, I don't do it with coins because they are a known weight/size as explained before.
Generally I test with a drop on undamaged surface (this will remove all patina/tarnish and leave you with slightly etched bright white silver), then if it passes, I will scratch with knife and retest, if its plated you will generally see a blue or green line where the scratch is surrounded by the red we all know is silver.
However you now have a scratched coin with a discolored area where the acid drop was sitting.
If I'm still not sure I'll cut the coin in half and sell it for scrap.
I find for silver the scraping on a stone like you do with gold is not very easy to use due to the dark color of the stone, I find putting drops directly on the item is the best way to go...
I don't deal in numis (don't have the contacts to sell nor the expertise in grading to buy right), I don't deal in large bullion bars, (people with these items want me to make too small a margin, and again I don't have the customer base to sell quickly, its not worth my time/opportunity cost since I don't hedge and don't have unlimited funds to buy) 10 oz silver bar is largest I've ever bought, 1 oz gold bullion is largest I've ever bought.