On: The problem of fake gold bars (2012)

[analog31]

What, run up and down the street naked, yelling Eureka?

Actually, I'm agreed that you could measure the density, but somebody could fiddle with the density too by adding just a touch of this or that to bring everything up to the right weight.

[diroussel → analog31]

Where 'this or that' can only be something more dense than gold, which are not cheap: http://m.wolframalpha.com/input/?i=10+densest+elements

[analog31 → diroussel]

Aha, I didn't look up the densities.

[SapphireSun → analog31]

You could always take small core samples and run them through mass spec.

[imaginenore → SapphireSun]

You suggest to drill every gold bar, thus ruining the certification?

[SapphireSun → imaginenore]

Random sample. I'm not familiar with gold bars, but I imagine that there are procedures for this (like rectifying at a new weight or recasting the sampled bars). A few milligrams of gold shouldn't be a big deal unless we're dealing with gold fever.

If you're willing to melt them down though, you probably don't have to deal with mass spec as some property will have to give (melting point, density, etc).