[Paladin2]

There are other material properties that could be used to find bars with a W core (e.g. Thermal expansion).

I'll have to look into alloys of W and Au.

[Renfield]

I suspect that Tungsten and Gold would not alloy well, because their melting points are so divergent. Maybe it could be done with crucible particle metallurgy.

[Usagi_yo]

I have no doubt that some gold bars have been compromised in some sort of scam, but at the national level? Too many ways to get caught. Besides gold bars don't move very quickly. If you discover one with Tungsten in side you pretty well much know where it came from. Besides, I find the post confusing. I don't know what it's asserting. Electrical resistivity of gold (20 °C) 22.14 nΩ·m Electrical resistivity of Tungsten (20 °C) 52.8 nΩ·m Thermal Conductivity of gold 318 W·m−1·K−1 Thermal Conductivity of Tungsten 173 W·m−1·K−1 Thermal expansion of Gold (25 °C) 14.2 µm·m−1·K−1 Thermal expansion of Tungsten (25 °C) 4.5 µm·m−1·K−1 Young's modulus of gold 79 GPa Young's modulus of tungsten 411 GPa

[RobertClark]

Ultrasonic is the best and least expensive method to check for the presence of W. The speeding of sound waves through W will only show half of the thickness of AU.