> verifying it is easy

Actually, it's not. It's nearly impossible to non-destructively distinguish gold from tungsten wrapped in gold.

Actually, not that hard. The speed of sound in tungsten is easily twice that of gold, hitting it with a hammer and analyzing the response on the other hand will easily tell you that it's tungsten or gold. In theory, a smartphone app could do it.

You can also test shear forces on the bar, a test you can perform easily at the bank itself (or any of the other material forces tests really). Those do usually require a bit of machinery.

Lastly, you can measure electric resistance. A gold bar will have a different resistance than a tungsten bar, especially if you compare a frequency sweep AC resistance vs DC resistance (if there is a difference, which should be about 20nOhm/m vs 50nOhm/m for Gold/Tungsten, you know the material has a core that is different from the outside).

> Lastly, you can measure electric resistance. A gold bar will have a different resistance than a tungsten bar, especially if you compare a frequency sweep AC resistance vs DC resistance (if there is a difference, which should be about 20nOhm/m vs 50nOhm/m for Gold/Tungsten, you know the material has a core that is different from the outside).

Electric current mostly travels on the surface of a material. Gold-plated tungsten might not have sufficiently different resistance from pure gold, if the plating is thick enough.

This is only the case in AC (skin effect). DC penetrates the entire conductor.

The higher the frequency the less you penetrate the material (self-induction in the material forces the electrons outwards).

This enables you to effectively do a sweep of material composition by increasing frequency and measuring the resistance. In theory you could even tell if the core was not conductive at all (due to the resistance not changing despite lower frequency).

So even if the plating was thick, you would be able to tell because the resistance curve begins to change at lower frequencies due to Tungsten having a higher resistance.

If your device is really accurate you could even measure the rough area of the core since skin effect is proportional to the square of the resistivity.

That's why it makes senss to only buy gold cast in a thin shape (like a coin). It's much harder to cast in any meaningfully large tungsten core and it significantly raises the likelihood of that fake core being discovered as one can verify the authenticity of the gold piece by scraping away a millimeter or two of gold using basic hand tools.

Considering how expensive gold is per ounce, it's not like any of us will be buying it by the bar.

Maybe not those massive bars, but if we’re talking about being in a country where you can’t trust the government at all with the currency, wouldn’t you want to store most of your savings in gold or something similar? So just thousands of coins I guess? Arr me matey

> where you can’t trust the government at all with the currency

Executive Order 6102.

If you're in a country where you can't trust the government, you lost. The government can take away your gold, your government can take away your bitcoins.

If "the government has become the enemy" is a problem, then you've got bigger problems at hand.

Any SEM with an EDS system will tell you non-destructively if you have tungsten wrapped in gold. X-Ray diffractometry would also do the same. Rutherford Backscattering spectrometry too. All three of these techniques are non-destructive and the first two are quite common to find at universities.

I guess you and I have different intuitions about the meaning of the word "easy".

That's quite a leap from "you can verify at some other gold dealer" though.

It is also a very large leap from “let’s just drill it at random locations” that an actual gold dealer will try first if they suspect something like this. The drill bit not going through the bar like butter at the location will probably be the first tip-off.

meanwhile verifying bitcoin is trivial. hackernews is the one demographic i was hoping would understand that. has something changed?

Do you have any first hand experience with buying gold from local dealers? I've never really looked into it but the vast majority of gold dealers in my city are also pawn shops geared toward purchasing gold rather than selling it. While I'm unsure as to their exact pricing model for selling gold, the way in which pawn shops are known to buy precious metals leads me to believe I'd be paying significantly more than whatever the current spot price is if I was to buy through them.

The safest way to buy physical gold is directly from a mint like the US or Canadian mint (obviously assuming you trust the government/mint in question).

The next best is to use a trusted dealer and buy the mint products that have verifiable serial numbers. For example:

https://www.apmex.com/product/98353/1-oz-gold-bar-royal-cana...

Canadian Mint 1oz bar, at a small mark-up over the price of gold. Comes sealed and has a serial number.

Now that is an actually reasonable markup. I guess my only concern there would be shipping, which can be insured but gets a bit pricey when you're insuring $1,200. Thanks for the link!

American Eagle Gold coins are US-Government issued, serial-number stamped official Gold coins of the US Government.

Created by the US Mint, you have strong assurances that you are recieving in fact, 91.67% gold / 22 karat (an alloy, because pure gold is too soft for the typical consumer).

If you do want 99.99% Gold / 24 karat, the US Mint also makes the Buffalo coin. But that's usually harder to store.

American Eagle coins are super easy to obtain and trade. Just go to any gold shop and ask for an American Eagle gold coin.

1 oz gold spot is $1210 per ounce [1]

1 oz American Eagle coin direct from the mint? $1,490 [2]

That's a 23% "transaction fee". You'll get much much lower buying gold (or bitcoin) from somebody else.

[1] http://www.kitco.com/charts/livegold.html

[2] https://catalog.usmint.gov/american-eagle-2018-one-ounce-gol...

You certainly don't buy gold coins directly from the mint.

You buy them at only a bit higher than spot price from 3rd party distributors. For example: https://www.apmex.com/product/1/1-oz-gold-american-eagle-bu-...

American Eagle coins have a slight premium, due to their guarentee by the USA Mint itself. If you don't care about serial numbers and want to just have bullion, you can buy other gold coins. But American Eagles are great because they are enforced by the powers of the US Government itself. So you get a bit of security (and therefore, the price of the coin is slightly higher compared to gold).

But not much higher. Really, it isn't. Checkout 3rd party sites like apmex or your local gold shop if you don't believe me.

The Gold Eagles sold direct to consumers by the mint are either "proofs" -- struck with a special finish, or a special minting targeted towards collectors. You're paying a premium for the "W" mint-mark and fancy box.

They also make a non-collector version and sell them to bullion dealers, who then mark them up modestly for retail. To get access to them direct, you're probably buying hundreds of coins at a time.

There are currency exchangers in every major city who trade BTC for paper cash, same as gold dealers.