3 ms·
Like saying "Beetlejuice! Beetlejuice! Beetlejuice!", post a coin article on HN and I shall appear ;) A few interesting (perhaps) tidbits of nerdery: 1: > "B
by nlh 3y ago
Like saying "Beetlejuice! Beetlejuice! Beetlejuice!", post a coin article on HN and I shall appear ;)
A few interesting (perhaps) tidbits of nerdery:
1:
> "But when Dr. Ortega and Ms. Bravo Hualpa bombarded the 1899 coin with X-rays and measured the light it re-emitted, they determined that the dinero was largely made of copper, zinc and nickel.
This sounds extremely fancy (and technically it is), but what you may find surprising is that the technique they used (XRF eg X-Ray Fluorescence analysis) is so useful in the coin/bullion industry that you can buy handheld "XRF guns" that perform a metal composition analysis on the spot and present the readout in a very easy-to-consume way on a small LCD screen. And you can buy them on Amazon!
https://www.amazon.com/XRF/s?k=XRF https://www.amazon.com/XRF/s?k=XRF
(They are not cheap.) But they are ridiculously useful and it feels like a magic trick to point it at a piece of metal and have an instant elemental readout. As you might guess, 99% of this is to check whether a piece of gold/silver is actually gold/silver.
2:
Unlike TFA's example, among US coins there are lots of counterfeits out there that ARE made out of the proper base metal (typically 90% gold, as much US gold coinage is composed).
Why on earth would someone do that? The answer is that in the mid-20th century, many countries (including the US) imposed restrictions on import and export of gold but had exclusions for certain types of currency. So one clever way to transport quantities of foreign gold into the United States was to make sure you were transporting exempted US currency. So many countries developed sophisticated counterfeiting techniques to turn non-US-coinage gold into US-coinage gold. This worked quite well for getting gold into the US but has been a thorn in the side of collectors here for a while, since you might buy a rare US gold coin that's actually truly made of gold and yet is still a counterfeit :(
- crazygringo 3y ago> since you might buy a rare US gold coin that's actually truly made of gold and yet is still a counterfeit :( That's fascinating! What a funny situation. Is there actually any way to detect a counterfeit coin that is made of the right materials? It seems like all you've got to go on is the physical shape and relief. But that seems far easier to match perfectly than paper bills. Is there at least any way to tell "old" counterfeits from modern ones?
- nlh 3y agoYes, thankfully, there is a way to detect the fakes. It's really about the level of detail that you look at. An untrained eye probably would not be able to tell the difference, but to someone who looks at the real deal day in and day out, the fakes are often very very easy to spot. Coin nerds study the real ones in excruciating detail - to the point that people catalog not only the various dies that were used to strike various coins but the states of those dies (i.e. Early die state == pristine coins. Middle die state == a crack or chip might have started to form which presents as a raised line or spot on the surface of struck coins. Late die state == chunks of the die might be missing.). This is often done through reverse engineering -- examining enough examples of struck coins to identify differences in the the dies used. The dies themselves can be identified through unique markers -- a polish line here, the exact positioning of a letter, a microscopic defect, etc. So when you are able to identify the known dies, a counterfeit will stick out like a sore thumb. And if it was made from a cast copy of a known-good coin, then those will have their own telltale giveaways. In short: The counterfeits will always have subtle differences.
- Ferret7446 3y agoAlthough if there were a fake that was not detected, how would you know?
- bookofjoe 3y agoPrecisely. Whenever someone is exposed for fraud I think to myself that there are many others succeeding under the radar, some spectacularly.
- crazygringo 3y agoOh wow, I never realized there could be that much unique information encoded in a die. I guess it reminds me of identifying typewriters as well. Fascinating! Thank you for your explanations -- learning stuff like this is why I come to HN.
- 3y ago
- TacticalCoder 3y ago> ... restrictions on import and export of gold but had exclusions for certain types of currency I think something not entirely dissimilar is still true in some cases: there are limits, in various countries around the world, as to how much you can cross the border with without warning the customs but for some coins it's the face value, not the actual value, that counts. So for example someone can take shitloads of $50 gold coins that are actually worth $2000 (instead of $50) and legally cross the border with 40x the actual limit without having to warn the customs. I may be mistaken though.
- joshstrange 3y ago> you can buy handheld "XRF guns" that perform a metal composition analysis on the spot Oh wow that's really neat, feels like something out of Star Trek (Tricorder). > (They are not cheap.) Ok, but what is "not cheap"? A hundred? A couple hundred? Might be a cool thing to have Clicks link Oh dear god, $20K-40K. Yep, I think I'll pass but super cool nonetheless. Thank you for introducing me to that technology!
- balderdash 3y agoWhat if the bullion is just plated/covered in gold?
- defrost 3y agoThe depth of X-Ray penetration is very likely sufficient to induce secondary rays from the covered over not-gold. Failing that there's still the old Eureka! standby of weight + water volume displacement. https://www.horiba.com/int/scientific/technologies/energy-dispersive-x-ray-fluorescence-ed-xrf/what-is-x-ray-fluorescence-xrf/ https://www.horiba.com/int/scientific/technologies/energy-di...