I thought the tests were interesting. Especially the deep resistance scan.
I think these typically do eddy current testing by running an alternating magnetic field and measuring the "drag" the material puts on it. Several metals testers use this principle.
Another one that's often used in expensive scans is sonar, to see for example if there is tungsten put into the middle of gold bars (very similar density as gold). A DIY version is an ultrasonic thickness gauge. Since the speed of sound celerity) depends on the material, this effectively tests the metal all the way through. For coins the "ping" test can be used, since a coin of known dimensions will have very particular harmonics of resonance.
Sometimes x-ray fluorescence (XRF) is used, but this just tests the surface. Since gold is so dense, it only tests a few microns deep. So heavily-plated items will be missed by XRF.
There’s acid testing it’s fairly cheap but destructive only worth doing if you’re melting down nigger jewelry.
Nondestructive testing
Calipers and a scale
Resonance for coins, there’s a phone app. For free or maybe $4.99 for extras. It listens to the ring, gold/silver should last and sound alive.
Magnet, you’ll need a strong one. gold and silver is a dielectric. A magnet will not stick, but it can cause attraction with motion.
Resistance testing $1-2k https://www.sigmametalytics.com/shop
XRF alloy analyzer is better starting at maybe $3k used and $20k new.
A better gold/silver/pawn shop will have one, and may even let you test stuff you aren’t selling to them.
Pain in the ass to lookup an xrf to buy most say contact us. What the fuck, I did contact you, I made a request to your web server pulled up the page got more info, and I still have to submit some form and wait for a human. I’m guessing they don’t want to deal with the little guy that’s only going to order one unit. But why not, maybe that little guy gets bigger some day. So annoying to get industrial supplies. I get it for uranium or acid or something. But what do you think I’m going to do with all the other stuff I still have to jump through hoops to order.
That's very interesting.
Especially the sound app for the phone.
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