This might be part of the reason why gold jewellery has an effectively higher spot price than coins or bars; it's really easy to do a crude assaying job on a ring or a chain, providing they're not too thick. Just cut the thing gently with bolt cutters, and check if the metal is consistent throughout. You can't do that with bars or coins, you need an x ray machine (which most people tend not to have)
Spot value doesn't have much to do with jewelry prices, its the craftsman's time and material/machinery costs that make jewelry expensive. You'll get nauseous if you run the numbers on a $1000 2 gram 14k gold ring. Much harder to test as well. If you are testing a pure gold bar and find anything out of the ordinary, its fake. With jewelry you can get false positives or negatives depending on whats in the alloys.
That said, people counterfeit gold, not that strange considering the amount of money to be earned doing so. Its not all that hard to test generic gold bars, the trick is with testing things that come in plastic slabs, or collectible things that you don't want to ding.
I've never quite been able to understand why people compare bitcoin, gold, and fiat at all. Fiat is not a store of wealth, its a currency or means of exchange. If you don't like the fiat system, just keep as much cash as you need to pay your bills, and put the rest into a store of wealth. Bitcoin and gold are both stores of wealth, but completely different investments. Gold has traditional commercial and industrial value. Bitcoin has value for all kinds of complex economic reasons I'm sure I'd butcher if I tried to repeat. Bitcoin is more unstable than gold, but it also has a greater gain/loss potential. They are very different investment vehicles.
Mix it up, hold Bitcoins and gold, and buy from reputable dealers if you want piece of mind. Its not worth saving $7 buying a gold bar on Ebay, unless you have all of the materials to accurately test it yourself, and have the time to fight with Ebay customer support when you claim the bar is fake. I've got all of the testing supplies, and will still tell you, I still prefer buying from a large company that is safe.
Funny, a comment on the vid was claiming that the jewelry pieces are easier to check since you can cut them easily and no need to use for an X ray.
On the other hand the claim is probably fake, another comment on youtube debunked it by calculating that 1 million of bars of that size are about 50% more than what the american government has 4000 tonnes more.
It does look helpfull tho and perhaps a wise idea to cut the bars if it's not possible to use a scanner.
