What the scammers do is hollow out real gold bullion bars and replace the missing gold with tungsten, then seal up the end with real gold, so from the outside it looks and feels like real gold bullion.
Tungsten density is 19.25 g/cubic cm and gold density is 19.30 g/cubic cm.
Only a very fine and accurate scale could tell the difference in weight.................
What is the smallest, in ounces, bars that you know of that have been compromised with tungsten?
Or a hacksaw. =;^)