How to test if conductor is copper or silver based

No such thing as commercially available pure copper or silver. Even the very best and most expensive cables use metals that have a very, very small amount of inpurities.

a jewelry store

Autosports - the best copper I know of is zero crystal 9N copper that is 99.9999999% pure or 7N silver that is 99.99999% pure.

Kenobi -testing for purity is very easy - just weight your banana plug (just the metal part) and then drop into water to calculate volume. Once you get density you know what it is. If banana plug won't give you accurate reading of displaced water - then use 1000 of them. I hope it was helpful.

One of my friends is working at the pawn shop and he had a customer who brought him a gold slab to sell. A monetary standard gold slab should weigh about 50 kilos and eventually it did, but he decided to drill a hole... After just less than millimeter of drilling the tin started to come up above the drill bit... What d'u think?

Marakanetz - Tin slab of the same weight is more than twice larger than slab of gold.