The coolest solution I've read about to note the producer is to emboss a hologram in the metal, though perhaps with enough care this too could be faked or copied:
The coolest solution I heard was to look at a well defined spot of the gold bar and register the impurities/bubbles/structure that naturally happen while casting. This is very difficult to reproduce (because there is no legitimate need to do so) and is already present.
There are other methods like this, Sunshine Minting for example has a 'decoding lens' for their products that contain the 'MintMark SI security feature'.
Geiger Edelmetalle , on their Geiger branded stuff, uses a a UV safety coating but it will rub off with enough handling (which is why many of us do not remove the shrink wrap they put on their bars), they also individually assign serial numbers that can be tracked online for gold and silver bars starting at 1 gram
lixtra|6 years ago
Edit: And of course put the info on block chain.
ryanmercer|6 years ago
http://www.sunshinemint.com/TechnologyEnhancements.aspx
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Geiger Edelmetalle , on their Geiger branded stuff, uses a a UV safety coating but it will rub off with enough handling (which is why many of us do not remove the shrink wrap they put on their bars), they also individually assign serial numbers that can be tracked online for gold and silver bars starting at 1 gram
https://www.geiger-edelmetalle.de/en/about-geiger/news/geige...