Dissolve a small representative sample in a test tube.
A quick 'on-the-spot' test though, a pencil eraser. A magnet. A file. A loupe. Known quality items to practice on.
Eraser can erase away the thin gold layer of ENIG as well as other plated items, and with practice, you can get good at guesstimating the yield per lb (gsp could, I cant do it if my life depended on it)
A magnet, obvious
A file, to file down into the substrate to get a good look at it. -dont use snips to just cut the end. The gold will 'smear' and make you think that you will be taking a treasure bath after refining the untold riches. ...then you will be sad, when you realize how you tricked yourself... ....not that its happened to me or anything. :roll: :evil:
A good loupe to check out the notch from the file
Practice makes perfect.
