# Japanese Gold Bars 999.9 **URL:** \ **Category:** Factual Questions\ **Created:** [November 2, 2019, 11:29am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908 "2019-11-02T11:29:46Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![RedSky](https://avatars.discourse-cdn.com/v4/letter/r/67e7ee/32.png) [@RedSky](https://boards.straightdope.com/u/RedSky)\ **Post date:** [November 3, 2019, 7:40am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/21 "2019-11-03T07:40:35Z")
> [@SamuelA](#): > > I always wondered how you can tell if a gold object is actually pure-ish gold, without melting it down. Sure, you could check density, but couldn’t someone mix lead and a lighter metal to create a core with the same combined density as gold? Then electroplate or melt on a thin outer gold layer, depending on the melting point of the eutectic metal core? > > Does NMR work on bricks of gold? I only ever got to use it in school on tiny test tubes. Bullion dealer have a variety of machines to measure the purity of your gold. One common test is a ring test where you measure the sound a coin makes when struck in a specific way, this is the same principle used for vending machines to accept or reject you coin. ---
**Author:** ![RedSky](https://avatars.discourse-cdn.com/v4/letter/r/67e7ee/32.png) [@RedSky](https://boards.straightdope.com/u/RedSky)\ **Post date:** [November 3, 2019, 7:42am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/22 "2019-11-03T07:42:14Z")
> [@SamuelA](#): > > I always wondered how you can tell if a gold object is actually pure-ish gold, without melting it down. Sure, you could check density, but couldn’t someone mix lead and a lighter metal to create a core with the same combined density as gold? Then electroplate or melt on a thin outer gold layer, depending on the melting point of the eutectic metal core? > > Does NMR work on bricks of gold? I only ever got to use it in school on tiny test tubes. Bullion dealer have a variety of machines to measure the purity of your gold. One common test is a ring test where you measure the sound a coin makes when struck in a specific way, this is the same principle used for vending machines to accept or reject you coin. ---
**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\ **Post date:** [November 3, 2019, 8:28am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/23 "2019-11-03T08:28:34Z")
> [@jnglmassiv](#): > > Video illustrating the density of gold: > [https://youtube.com/watch?v=iz27orlBBDU](https://youtube.com/watch?v=iz27orlBBDU) > A museum in Japan offers a challenge to pull a 12.5 kilogram bar of gold through an elbow-sized hole in a box. Good one. I had a similar experience, but with a bigger “brick” of gold that was about 4x the size of the one in that video. It was in the Philippines, at a Benguet gold mine, The brick was not in a box, it was laying on a table and we were there during a gold pour so the temps in there were pretty hot. There was plenty of armed security around our tour group of friends of a Benguet Corporation exec. The challenge to us was if anyone could pick up that brick with one hand, we could keep it. We tried, and of course we could not. It weighed about 100 pounds. Changing subjects, I work at a surgical robotics company that makes a radiation oncology linear accelerator — a linac for short. The radiation is shielded, in part, by tungsten. I have a scrap piece of tungsten that’s about the size of a brick, and the thing is heavy! The manufacturing guys gave it to me, and I use it as a doorstop. In rough numbers, - 197 is the standard atomic weight of gold, Au. - 207 is the standard atomic weight of lead, Pb. - 185 is the standard atomic weight of tungsten, W. So Pb, lead, is about 5% heavier than gold. So W, tungsten, is about 6% lighter than gold. And tungsten is about 12% lighter than lead. I plan to keep that chunk of tungsten as a linac souvenir (of sorts). ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [November 3, 2019, 9:55am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/24 "2019-11-03T09:55:35Z")
Atomic weight and density are not the same. ---
**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\ **Post date:** [November 3, 2019, 9:57am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/25 "2019-11-03T09:57:14Z")
I didn’t say they were. Maybe somebody else did. ---
**Author:** ![Isamu](https://avatars.discourse-cdn.com/v4/letter/i/7c8e57/32.png) [@Isamu](https://boards.straightdope.com/u/Isamu)\ **Post date:** [November 3, 2019, 9:58am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/26 "2019-11-03T09:58:47Z")
> [@markn\_1](#): > > Regarding the OP’s claim that you’ve seen gold classified on a 100-point scale, like 99.9 – where have you seen that? . [https://www.perthmint.com/catalogue/australian-kangaroo-2019-2oz-gold-proof-high-relief-coin-aua-auk.aspx](https://www.perthmint.com/catalogue/australian-kangaroo-2019-2oz-gold-proof-high-relief-coin-aua-auk.aspx) “Proof quality 99.99% pure gold with high relief strike” at this website. Quite common for coins, I thought, but I am not an expert. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [November 3, 2019, 11:32am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/27 "2019-11-03T11:32:52Z")
> [@Bullitt](#): > > … So Pb, lead, is about 5% heavier than gold. > So W, tungsten, is about 6% lighter than gold. And tungsten is about 12% lighter than lead. n my dialect, “heavier” here means “has a higher density.” ---
**Author:** ![Isamu](https://avatars.discourse-cdn.com/v4/letter/i/7c8e57/32.png) [@Isamu](https://boards.straightdope.com/u/Isamu)\ **Post date:** [November 3, 2019, 11:33am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/28 "2019-11-03T11:33:33Z")
I think I may be stupid about numbers. So in 100 terms, what is equal to 999.9? 99.999? ---
**Author:** ![JoseB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/joseb/32/1530_2.png) [@JoseB](https://boards.straightdope.com/u/JoseB)\ **Post date:** [November 3, 2019, 1:20pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/29 "2019-11-03T13:20:07Z")
> [@Bullitt](#): > > In rough numbers, > > - 197 is the standard atomic weight of gold, Au. > - 207 is the standard atomic weight of lead, Pb. > - 185 is the standard atomic weight of tungsten, W. > > So Pb, lead, is about 5% heavier than gold. > So W, tungsten, is about 6% lighter than gold. And tungsten is about 12% lighter than lead. > > I plan to keep that chunk of tungsten as a linac souvenir (of sorts). Uhhh… what? Atomic weight has no bearing with the density of an element… which is what determines what is “lighter” or “heavier” when put on a scale. Lead has a density of 11.34 g/cm3. Good has a density of 19.32 g/cm3. Tungsten has a density of 19.3 g/cm3. As can be seen, lead is roughly 41% **lighter** than gold, and tungsten and gold are basically equally heavy (gold is a smidge heavier). ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [November 3, 2019, 2:29pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/30 "2019-11-03T14:29:45Z")
> [@JoseB](#): > > Uhhh… what? Atomic weight has no bearing with the density of an element… Nitpick: While density and atomic weight are different there is _some_ correlation (“bearing”), as suggested by this list: .071 liquid hydrogen (AW 1) .125 liquid helium (AW 4) 8.96 copper (AW 64) 10.5 silver (AW 108) 19.3 gold (AW 197) 19.1 uranium (AW 238) ---
**Author:** ![DesertDog](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/desertdog/32/11503_2.png) [@DesertDog](https://boards.straightdope.com/u/DesertDog)\ **Post date:** [November 3, 2019, 3:08pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/31 "2019-11-03T15:08:07Z")
> [@asterion](#): > > Collectors want high-purity gold because of the value. Industry wants high-purity gold for industrial purposes. As mentioned, most commercial gold is lower purity because pure gold is too soft and heavy to really want for applications like jewelry. 24kt gold jewelry is (or at least was) popular in Asia as an easy way to carry around escape money in case things went pear-shaped. It does bend easily, though, more so than most people would want. > [@Isamu](#): > > I think I may be stupid about numbers. So in 100 terms, what is equal to 999.9? > > 99.999? That would be 99.99% Au. I recall reading when I was young that the Soviets produced “5 nines” gold for the sheer bragging rights. It would sell at a premium because there was a dab more gold in it but most producers figured the extra refining expense was not worth it. ---
**Author:** ![SamuelA](https://avatars.discourse-cdn.com/v4/letter/s/c77e96/32.png) [@SamuelA](https://boards.straightdope.com/u/SamuelA)\ **Post date:** [November 3, 2019, 3:50pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/32 "2019-11-03T15:50:32Z")
> [@Melbourne](#): > > And there are a lot of tungsten gold bars out there. > > There is a huge Chinese industry making fake gold bars of various qualities, and they certainly have the technology to make tungsten gold bars (which, although too expensive for cheap fakes, are much cheaper than real gold bars). And the Chinese have famously accused the USA of being the source of tungsten gold bars. So are the X-ray fluorescence spectrometers not commonly used? It seems like the obvious thing to do before accepting a gold bar worth hundreds of thousands of USD at a minimum. Stick it in the machine and make sure it’s actually gold in the middle. Googling for it, apparently there are hand held machines that look like a bar code scanner?! I’m not sure how this is remotely radiation safe, and I’m not sure they can measure the middle of a gold brick, but anyways… ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [November 3, 2019, 3:58pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/33 "2019-11-03T15:58:44Z")
> [@DesertDog](#): > > 24kt gold jewelry is (or at least was) popular in Asia as an easy way to carry around escape money in case things went pear-shaped. It does bend easily, though, more so than most people would want. In Thailand, jewelry and bars are 96.5%, or about 23 Karats. (Some foreigners complain that this will make their “go bag” useless for travel to the West. But carrying gold bullion across borders isn’t high on my To-Do list. :rolleyes: ) ---
**Author:** ![Bullitt](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bullitt/32/5725_2.png) [@Bullitt](https://boards.straightdope.com/u/Bullitt)\ **Post date:** [November 3, 2019, 4:08pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/34 "2019-11-03T16:08:02Z")
> [@JoseB](#): > > Uhhh… what? Atomic weight has no bearing with the density of an element… which is what determines what is “lighter” or “heavier” when put on a scale. > > Lead has a density of 11.34 g/cm3. > > Good has a density of 19.32 g/cm3. > > Tungsten has a density of 19.3 g/cm3. > > As can be seen, lead is roughly 41% **lighter** than gold, and tungsten and gold are basically equally heavy (gold is a smidge heavier). Oh okay thank you **JoseB** , and **septimus** too. This makes sense. Sorry for the confusion! ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [November 3, 2019, 9:45pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/35 "2019-11-03T21:45:58Z")
> [@SamuelA](#): > > So are the X-ray fluorescence spectrometers not commonly used? It seems like the obvious thing to do before accepting a gold bar worth hundreds of thousands of USD at a minimum. Stick it in the machine and make sure it’s actually gold in the middle. > > Googling for it, apparently there are hand held machines that look like a bar code scanner?! I’m not sure how this is remotely radiation safe, and I’m not sure they can measure the middle of a gold brick, but anyways… Dunno. But in the past they have drilled when there was uncertainty of supply, and, when the gold comes from a trusted supplier, that’s also the point of serial numbers. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [November 3, 2019, 11:14pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/36 "2019-11-03T23:14:59Z")
> [@SamuelA](#): > > Googling for it, apparently there are hand held machines that look like a bar code scanner?! I’m not sure how this is remotely radiation safe, and I’m not sure they can measure the middle of a gold brick, but anyways… X-rays are EM that is typically generated by a simple electric process in a powerful vacuum tube. In general, the radiation goes where you point it and is negligibly reflective, so the x-rays themselves are not very hazardous, there are no radioactive isotopes involved, and the detection process is about the observable effects of the x-rays on the material, which generates lower-energy EM. It could very easily be radiation safe. ---
**Author:** ![Isamu](https://avatars.discourse-cdn.com/v4/letter/i/7c8e57/32.png) [@Isamu](https://boards.straightdope.com/u/Isamu)\ **Post date:** [November 4, 2019, 1:45am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/37 "2019-11-04T01:45:46Z")
> [@DesertDog](#): > > That would be 99.99% Au. . So there is, in fact, no reason to write 999.9 gold rather than 99.99. OK. ---
**Author:** ![eschereal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/eschereal/32/18939_2.png) [@eschereal](https://boards.straightdope.com/u/eschereal)\ **Post date:** [November 4, 2019, 2:39am UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/38 "2019-11-04T02:39:04Z")
> [@Isamu](#): > > So there is, in fact, no reason to write 999.9 gold rather than 99.99. OK. Well, there is, because the value is called “[Fineness](https://en.wikipedia.org/wiki/Fineness)” and it is expressed as a parts-per-thousand number. If you speak of 99.99 gold, you are talking about 2.4 karat gold, which is mostly something besides actual gold. ---
**Author:** ![Hermitian](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hermitian/32/470_2.png) [@Hermitian](https://boards.straightdope.com/u/Hermitian)\ **Post date:** [November 4, 2019, 1:54pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/39 "2019-11-04T13:54:53Z")
> [@Isamu](#): > > So there is, in fact, no reason to write 999.9 gold rather than 99.99. OK. > [@eschereal](#): > > Well, there is, because the value is called “[Fineness](https://en.wikipedia.org/wiki/Fineness)” and it is expressed as a parts-per-thousand number. If you speak of 99.99 gold, you are talking about 2.4 karat gold, which is mostly something besides actual gold. So the reason is basically: “that is the way we in the gold community have always done it despite the fact that it doesn’t match the way anyone else expresses completeness.” You could make a case that “we have always done it that way” is not really a _good_ reason. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [November 4, 2019, 2:38pm UTC](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908/40 "2019-11-04T14:38:12Z")
> [@eschereal](#): > > If you speak of 99.99 gold, you are talking about 2.4 karat gold, which is mostly something besides actual gold. At the risk of winning Today’s Most Obvious Nitpick award: If someone speaks to you about 99.99 gold, they’re referring to 999.9 gold, and NOT 2.4 karat gold. hth. [Previous page](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908.md?page=1) [Next page](https://boards.straightdope.com/t/japanese-gold-bars-999-9/842908.md?page=3)