Discussion in 'Bullion Investing' started by Jim C (Mich), Jul 31, 2020.
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This is why rounds sell at a discount to coins. Coins have published and strictly adhered to standards. This makes it easier to verify authenticity. only true way to verify rounds or bars is to melt them down.
Isn't it easier to use an XRF Analyzer? ~ Chris
If someone has this expensive piece of equipment. Does it also verify thickly coated bars with proper weights? Would it have caught those tungsten gold bars in China? Silver is extremely easy to imitate SG with other metals.
How should I know! I can't afford one. ~ Chris
Trust But Verify
Strong magnet, Scale, calipers...metal detector.
XRF only penetrates slightly below the surface. The depth depends on the metal and energy of the beam. I generally figure 100 microns +/- (0.1 mm) for handheld units based on stuff I've read in the past, but that's just a gut feel number. I hope the scientists will correct me if I'm way off base.
Thick plating can fool XRF. I think that's how the gold plated tungsten bars fooled people.
Interesting! I wonder if there are any members who are more familiar with the operation of the XRF Analyzer. @desertgem ?
Basically, the XRF unit generates an xray beam. As that beam hits an atom, it knocks off an electron close to the nucleus. The atom isn't happy losing this electron, so an electron in a higher energy orbit will drop into the lower energy orbit to stabilize things. When it does, a small amount of energy is released as an xray
Each element has very specific energy levels where the electrons orbit around the nucleus and it's different for each one (there are multiple orbits or shells for each element). So, if you can measure the amount of energy released by the electrons and match it with known values for a specific element, you can figure out what you have.
Sounds simple, but it still blows me away that we can do this.
This also explains why XRF can only detect elements near the surface. As the X-Ray beam starts penetrating the surface it loses energy. At some point below the surface, it doesn't have enough energy left to knock off electrons. Plus, if it does knock off any election below the surface, the resulting X-Ray energy may not make it back to the surface to be detected.
This is what the data usually looks like. You need to take this data and convert it to the percentages that are displayed on the XRF screen. That requires a lot more math which is beyond my pay grade. But I'll just say that because of the complexity, handheld units may not have as detailed algorithm as you would find in a laboratory machine, so measuring of trace elements (less than a percent) or values reported to 0.01% may not be the most accurate
If the weights are the same and they're from a trusted seller, I wouldn't sweat it. My guess is that they may have used different collars for the two designs. Is there any difference in the edge designs of the two?
More likely it's the emitter, detector and analog signal-processing stuff that gets bulkier and more expensive if you need those extra digits of precision. Not to mention the safety equipment -- you get more signal if you dump in more X-rays, but you also get, well, more X-rays.
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