Yeah, people are definitely going to be pretty worried about their physical... But I suspect *most* (in private hands, at least) will be found to be legit. Cheap testing equipment will proliferate a bit, and this will blow over. Obviously, I could be wrong, but these things generally tend to get blown out of proportion...

You're looking at this as really bearish for gold. What about the flipside argument? If there really *is* widespread fraudulent physical gold (say, more than 15% of what's in private hands), that instantly reduces what people thought the supply of physical gold was, therefore bumping the price?? Maybe this just causes a big spread to develop between paper and (legit)physical... ?

Disclosure: I'm neither bullish nor bearish on gold. Too much variance on all the variables, leading to statistical noise in aggregate, in my opinion... Bitcoin, on the other hand, I'm pretty bullish on. And yeah, good luck filling bitcoin with tungsten.

imagine if just one Bitcoin was found to be filled with "tungsten" metaphorically; it would destroy the entire Bitcoin concept.

now you can say that it would be different somehow for gold or silver if "just 5%"  or even "1%" were fake b/c of its thousand year history but do you really think that will be the case?  how many of you can stand to have 5% of your stash to be fake?

  If it was even as widespread as 1% counterfeit, we'd be seeing 100s of examples on social media and news stories.. Not the same 10 oz bar over and over again.

I also don't think it's a game changer, since there is already good solutions to solve it.
Even if cheap ultrasound testers are not good enough, then I guess at least the big dealers will be able to buy good ones.

How can it be possible to solve that ? There will always be people making fake coins/bars, like n8rwJeTt8TrrLKPa55eU showed it's not a new problem. History shows it didn't prevented gold/silver to impose itself as money in history.
It's an arms race between people making these bars and people testing them. And people testing are winning. If these bars were not detectable without melting it, that would be a real problem.

in fact, i'm sitting right here twittling a one ounce gold coin on the table and wondering what the hell is inside.

Wow, What the hell is happening. Someone is dumping PM, and cypherdoc didn't post here yet 
Hope everything is ok for you.

On a side note, I'm happy I didn't took your bet 
But If you are sad about that, we can double the previous one (1500$ vs 1900$)