As tungsten is nearly identical in density to gold you could have a bar that is 50-50 Au/W and still make a huge profit. Heck even a 95/5 bar would be highly profitable.
Fake, fake , fake
There are a lot of gold sale companies with mud and slime on their faces:
This was exposed several years ago. There were purchases of tungsten bars shaped like gold bars (hundreds of them) and it was assumed the Chinese were making fake gold bars.
I have always wondered if you couldn’t relatively easily use some other physical property to non destructively distinguish gold and tungsten. The speed of sound in gold is about 3240 m/s, in tungsten 5200. It should be relatively easy to instrument a test that measures the “ringing” of a bar in response to an acoustic signal, and use it to characterize gold vs. tungsten.