Use a hard drive magnet. Either neodymium or colbalt they are the strongest non electric magnets. Anything that sticks will be on steel or nickel. There's a fair bit of difference in the base metal value but at this point it's not what you're looking for. Both types are very common and you're facing a major task sorting these two apart.
Slightly sticks. These will be gold plated stainless, or chromium nickel. The base value spread is less than ten cents. So in this class not worth sorting at all between the base metals. Stainless 300s is 70-90 cents and chromium is 80-1.10 per lb.
Finally no stick. These are your key to find here. These you should try to bend. You're unlikely to have many. If it bends easily it's on copper, silver, or is an alloy, most likely 8/10/12 kt If they don't bend at all they're plated manganese and the base is about 40-55 cents per lb.
If they bend with some effort it's brass or cast copper underneath. Base is $1.20-$2.10 per lb.
_________________ -- my grades are my own and do not represent an offer from boardsort, nor are they guaranteed. Please keep that in mind.
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