You need coins. You can't walk around with a gold bar. I would say silver coins to keep the value down, too.
As a "my government made our money useless" back up. USD cash are good too unless you are American, obviously.
I think that's where you first get into "some other governments money may be less useless" as a first stage backup. Precious metals in direct ownership are really a hedge against all or most other governments money collapsing.
Until you reach a global societal collapse, having gold in your possession seems like a negative ROI and I wonder if, should that case happen, would precious metals again become the medium of exchange or something else (peoples' opinions have changed and a fist full of diamonds might not be as valuable to me as say fresh drinking water should such a thing happen). It would likely depend on the cause of global collapse and what people consider valuable (obviously, but it probably needs stated).
Precious metals seem to be a good medium of exchange historically only at a certain level of assumed societal infrastructure, similar to our fiat currencies. Cavemen and small tribes cared little of precious metals and would rather trade land, access rights, livestock, etc.
They are not placing fake gold into real packaging. They are manufacturing the counterfiet packaging themselves.
Gold-plated lead would instantly be discovered if it was measured by weight AND dimensions.