[Wonder Warthog]

"That would not detect these bars. They are surrounded by a fairly thick gold layer, not gold plated."

Without knowing the specifics of the detector, you cannot make such a judgment (what energy/intensity of x-ray source, sensitivity of detection). Some XRF devices will probably not work, some will work. But this is a very specific application. I'm sure some mfg. will come up with a dedicated device that targets this specific application.

Believe me, I understand the physics here. My minor subject in grad school was nuclear science, a fair segment of which was about non-destructive testing using radiographic devices. I'm sure plain old x-radiography with Co-60 and film would quickly distinguish such fake bars....and that the new fully electronic and computerized (and much more sensitive) detectors would do even better.

[ltc8k6]

You can see in the pics that the layer of gold is quite thick. I doubt the bars would get far if they could be detected so easily.

They know such checks are going to be done. They know gold plating will not work. That’s why they go to the trouble of hollowing out actual gold bars.

I’m actually far more interested in how they are hollowing out the actual gold bars, and how they are sealing them up again without this being visually noticeable.

[ltc8k6]

The bars have passed the handheld XRF scans we are talking about.

http://silverdoctors.blogspot.com/2012/03/tungsten-filled-1-kilo-gold-bar.html

“In the biggest news we’ve broke since the JP Morgan whistle-blower stepped forward,
Australian Bullion Dealer ABC Bullion has contacted SD to advise that one of its suppliers has provided them photographic evidence of a tungsten filled 1 kilo gold bar discovered this week. The bar passed a hand-held xrf scan which showed 99.98% pure AU. The tungsten was only discovered when the bar was physically cut in half.

...”

[PapaBear3625]

Simple test, taking advantage of the fact that gold has half the electrical resistance of tungsten, use a Wheatstone bridge:

Zero current will flow through the galvanometer at the center if

Use a known-good gold bar or coin as your reference. If a supposedly identical bar or coin displays different resistance, then it is fake.