Official Gold coin specification vs theoretical weight
 

Hi,

Following a recent (closed) thread reporting fake austrian philharmonics gold coins, I decided to do the following calculations based on a theoretically perfect gold disk (without any depressed field) to see how it was possible to make a .900 fine phili copy with still the same weight but be even thinner.

The calculations are based on the surface of a perfect circle (pi * r * 2), the volume (surface * height), and the weight/volume constant for the metals in question.

In the case of a normal phili, if it was a solid and plain 9999 gold disk, it would be:

surface: 3.141592 * (3.7 cm/2) * (3.7 cm/2) = 10.7521 cm(2)
height : 0.2 cm
volume: surface * height = 2.150 cm(3)
weight: 19.30g / cm(3) * 1.505 cm(3) = 41.503 g

But because the coin field is less than 2 mm (the field is less thick), and less wide (the ridded edge is not plain) it gets lower than 41.5g.

Now that I look at it, does anyone has a real gold philharmonic coin that can test its specifications? I'm starting to think that the Austrian mint official specs are quite approximative.

Now, if the phili would be .900 gold instead of 9999, and 1.65 mm thick. Assuming a solid disk, and the .100 part made of silver, that would make it:

surface: 3.141592 * (3.696 cm/2) * (3.696 cm/2) = 10.7288 cm(2)
height : 0.165 cm
volume: surface * height = 1.7702 cm(3)
density of .900 gold, .100 silver: = (19.30g / cm(3) * 0.900 + 10.49g/cm(3) * 0.100 = 18.419 g/cm(3)
weight: 18.419 g/cm(3) * 1.7702 cm(3) = 32.606 g

Now, accomodate for the lower field and rim, and you can easily reach 31g, a full troy oz.

You can see that a .900 gold coin can be made into a phili disc spec (even thinner), but with a higher field than the genuine article, and still be real .900 gold.

I think that's the solution of the puzzle. Now, if that's true, the .900 phili should have the field much higher than the genuine article, and less relief. Can someone post a high resolution scan of an (alleged) real austrian gold philharmonic coin?

Lets take a Gold Maple for example, according to the official specs are 30 mm wide, 2.87 mm thick, so it makes, if it were a solid gold disk:

surface: 3.141592 * (3.0 cm/2) * (3.0 cm/2) = 7.06858 cm(2)
height : 0.287 cm
volume: surface * height = 2.0286 cm(3)
weight: 19.30g / cm(3) * 2.0286 cm(3) = 39.15 g, which is less than the phili specs, but still leaves a wide margin for the depressed field.

Now, the 1 million dollar question, who would go out of their way to produce such .900 fake phili?

Re: Official Gold coin specification vs theoretical weight
 

Good thread, but I'm already confused by all these numbers. :111:

Anyway, it just seems to be that there could be zero room for any "tolerance"/variation in specs, since even a disc of 37mmX1.95mm of .999 would have less weight than 37mmX2mm of .999.

The coin in question weighed exactly 480 grains.


I also noted that there are other incentives beyond financial ones to counterfeit a coin like this.

Re: Official Gold coin specification vs theoretical weight
 

I measured my lucky Gold Philharmonic which I keep on my office desk, minted in 1991. The measurements are:

Weight = 31.2 grams (1.003 troy oz.)
Diameter = 37 mm (see scans below)
Thickness = 2 mm (see scans below - small division=1 mm)

The hi res scans below will allow for a direct comparison of my genuine (hopefully!) coin and that of TheSkeptic, the purported fake:

Re: Official Gold coin specification vs theoretical weight
 

Well, my whole point is that it's possible to make a fake Austrian Philharmonics coin that is only .900 fine gold, but is 37.0 mm wide and 1.65m thick, by simply using a normal gold/silver alloy.

All the trick is in using low relief strike.

What is strange, though, is that

1) It would have been easier (and cheaper) making the coin 2.0 mm, and would have then have the exact mint specifications.

2) It would have been cheaper to produce at 2.0 mm.

So the motivations behind the production of that coin are, to me, very strange.

Re: Official Gold coin specification vs theoretical weight
 

Have you got a high precision caliper by chance to measure the thickness?

I use that one, and it works great.

Re: Official Gold coin specification vs theoretical weight
 

No I don't have one - but I just bought that one!!!

Anyway, my scan clearly shows that the coin is spot on at 2mm, and certainly not measurably less than 2 mm.

Re: Official Gold coin specification vs theoretical weight
 

I asked about that in a previous thread.

Where the OFFICIAL Royal Mint specification for the PROOF half sovereign are incorrect.

Re: Official Gold coin specification vs theoretical weight
 

Based on what I've heard, I think it's a problem with the acid test or its application in this instance. The existence of a .90 but otherwise perfect Philharmonic requires too many oddities and assumptions. I invoke Ocam's Razor.

-------------------------
http://farm3.static.flickr.com/2416/...46f3bc57_b.jpg

http://farm4.static.flickr.com/3018/...1f890083_b.jpg

Re: Official Gold coin specification vs theoretical weight
 

A low-relief/high field .900 fake presents another problem for the counterfeiter --- detectibilty certainly with a 10X loupe and probably even with the naked eye.
So it fails the fisch test or calipers and the design looks suspish ta boot. I'd pass on it in any case.

Re: Official Gold coin specification vs theoretical weight
 

2000 Schilling coin from year 2000

just measured on my desktop.

the thickness measurment is tenuous at best. If I slide in the calipers until I just feel resistance, the result is as shown.

If I press harder, I can get it to squeeze in to 1.88 mm.

Re: Official Gold coin specification vs theoretical weight
 

Yep, I knew it...I knew it! It's spreading. That coin's too thin RossL, and could be a fake from the looks of it. Might be an infamous Y2K Phil Fake coin. You'd better send it to me so I can have have a look see. I wouldn't want you to lose sleep over this.:36_3_13:

P.S. Squeezing hard often works with the ladies, but not with gold bullion coins - just wanted you to know that.

Re: Official Gold coin specification vs theoretical weight
 

Can you do another test: can you avoid the rim and just squeeze on the face of the coin? It looked to me like that was what was happening on the other coin.

Re: Official Gold coin specification vs theoretical weight
 

And for the record, I just got back from a fishing break and I dropped by lucky Gold Philharmoinic in the lake! :wink:

Re: Official Gold coin specification vs theoretical weight
 

OK, the only way I can measure inside the rim is to get the rim in the slot in the calipers. See first pic.

In the second pic you can see the results


PS ... I'm going fishing this afternoon.

Re: Official Gold coin specification vs theoretical weight
 

Dumbass :s1:! Sorry for the personal attack, but I mean, you should know better.

Re: Official Gold coin specification vs theoretical weight
 

No, you're right - stupid thing for me to do, while tying on a blood worm no less. My fishing partner chuckled and then said: "Aw don't fret over it mambie, 'twas probably fake anyway. Next time, buy a gold buffalo!"

Re: Official Gold coin specification vs theoretical weight
 

That's exactly what I wanted you to do and I think consistent with the original post. If you go to his video:


and look at 50 seconds in, you can see his caliper. His caliper has a notch on both sides (whereas yours appears to have a notch on only one side http://goldismoney.info/forums/attac...1&d=1248278560).

It looks to me like he is placing his calipers around the rim and measuring just the face of the coin. When you do that (with a calipers notched on *one* side), you get about 0.2 mm less than spec. Presumably, if you did that with a calipers that was notched on both sides, you'd get about 0.4 mm less. I think that's whats going on here.

Thanks.

Re: Official Gold coin specification vs theoretical weight
 

My caliper is notched on both sides, but the inside notch is less than the outside notch. Just by looking at it, the inside notch is maybe half a millimeter. It should be enough to miss the rim.

Re: Official Gold coin specification vs theoretical weight
 

OK, in the video, he squeezed in the calipers hard, and the coin could be about the same as mine. As I said before, I can make the reading change by about .1 mm just by squeezing.

It is possible the coin could be real and the acid tests and assays are wrong.

If it's a fake, it is 90% gold and 10% of something significantly heavier than gold and made with very high quality dies.

Re: Official Gold coin specification vs theoretical weight
 

Yes, you're right, good point, he was measuring the inside field thickness.

As you said, it's .2 mm less than spec, and an even wider margin to make a 'low relief' strike .900 fine possible, as follows:

surface: 3.141592 * (3.696 cm/2) * (3.696 cm/2) = 10.7288 cm(2)
height : 0.185 cm
volume: surface * height = 1.9848 cm(3)
density of .900 gold, .100 silver: = (19.30g / cm(3) * 0.900 + 10.49g/cm(3) * 0.100 = 18.419 g/cm(3)
weight: 18.419 g/cm(3) * 1.9848 cm(3) = 36.559 g

Re: Official Gold coin specification vs theoretical weight
 

I do not have a 1ozt version of the gold phil and I do not know how the fractional phils compare (they have polygonal cross reeded edges) buuuut, I do have several 1ozt silver phils and one of my favorite features of the coin is that the rim is significantly thicker than the faces.

I did not want to join the fray in the previous thread but that was my assumption all along (the inconsistent thickness). The acid test was the disconcerting part, for me.

Re: Official Gold coin specification vs theoretical weight
 

This is a micrometer, it's the way you make precise measurements like we're looking for. This has a ratcheting mechanism on the tightening knob so you don't overtighten. Anyone have one of these and a handy gold Phil? My Phils are in a sdb about 25 miles from here.

Re: Official Gold coin specification vs theoretical weight
 

I don't have a micrometer.

Following all the above calculations, with the rim at 2mm, a real Phil has to have the field of the coin less than 1.5mm thick.

Re: Official Gold coin specification vs theoretical weight
 

surface: 3.141592 * (3.696 cm/2) * (3.696 cm/2) = 10.7288 cm(2)
height : 0.185 cm
volume: surface * height = 1.9848 cm(3)
density of .900 gold, .100 silver: = (19.30g / cm(3) * 0.900 + 10.49g/cm(3) * 0.100 = 18.419 g/cm(3)
weight: 18.419 g/cm(3) * 1.9848 cm(3) = 36.559 g

Play with the above a little and to solve for the uniform thickness of a Philharmonic. The 207.066 figure below is the surface area in cm times specific gravity of pure gold (19.3)

207.066X = 31.13

This means that a pure gold cylinder blank that weighs 31.13 grams and is 37mm in diameter has to be 1.503 mm thick. I'll solve this, I'll just drive down and get a Phil and mic it. I need better pictures of a Phil anyway.

Re: Official Gold coin specification vs theoretical weight
 

That's a good thing to verify. To be more precise, it should be 1.4988 mm thick, so that a plain gold disc of 37.0 mm would weight exactly 1 troy oz. Considering the rim and the devices, it should be even thinner.

Got the calculation from the following data:

31.1034768g / 19.30 g/cm^3 = 1.6116 cm^3
pi * (37.0 /2)^2 / 1.6116 cm^3 = 0.14989 cm = 1.4989 mm

Re: Official Gold coin specification vs theoretical weight
 

I am not intimately familliar with the minting process, nor do I want to sit here and run the numbers (I am a MET, I can, I am just lazy).

Is it possible that the blank planchet is smaller than the finished dimension and the soft gold "flows" between the dies to fill in the details during minting? This would account for the shallow field and the raised rim.

Re: Official Gold coin specification vs theoretical weight
 

It's normal that coins have shallow fields are raised devices and rim.

Although normal, 'TheSkeptic' .900 fake phili made be realize that it's possible making fakes with less gold by taking advantage of the depth of the field, making coins that have slightly less deep field, but have otherwise perfect specs - only with less gold, of course.

The difference in density of 9999 gold and .900 gold-silver alloy is only 4.5% lighter (19.30 vs 18.419 g/cm^3).

Although in that .900 phili's case, the thickness was too thin even.

Re: Official Gold coin specification vs theoretical weight
 

And I thought that I was the only only one left who has a mic, Browne & Sharpe. Sorry though, no gold Phillies.

Re: Official Gold coin specification vs theoretical weight
 

A Lesson from History - Counterfeit Gold
By Kenneth M. Rutherford
President of Fisch Instruments

"It may be safely stated that the art, as pursued in the United States, is without parallel, and that without vaunt or hyperbole, we can 'beat the world' on this our national 'specialtie'- counterfeiting." (An anonymous writer in 1863).



Gideon B. Smith patented a counterfeit gold coin detector in 1853, the first in a long line of fake detectors patented over the next 30 years. They were borne out of a need for a surer, more positive method of identifying fake gold coins. The methods that had been used since the early 15th century were no longer suited to the rapidly developing commerce and business of the 1850's.



The detection of fakes was a serious business as the buying power of even a minor coin was great. The businessman of the time depended on a variety of checks, plus personal observation, to determine if the offered coin was genuine. These checks included spitting on the coin, or scraping it and then rubbing it against the short hairs on his head to make the base metal in a counterfeit show through. The coin was also dropped on a hard surface-a counterfeit having a different 'ring' to a genuine coin. Considering these methods, it is not surprising that the fake detector soon became as common in business as the electric calculator is today. The Gold Prohibition Act of 1934 calling for the confiscation of all gold coins, except those considered 'rare', marked the disappearance of the fake coin detector.



The money in everyday use changed from coins of intrinsic value such as gold, silver, and copper to paper, coins of the cheaper metals and plastic cards. The low buying power of everyday metal money eliminated the danger of counterfeiting and the lesson of history has been forgotten by many.



The metal money counterfeiter has not gone away and neither has his target changed: It is still the coins of high intrinsic value and buying power. These are the gold bullion coins owned by an estimated 5 million Americans. The risks to investors are great: He or she mostly knows little about gold coins (how often have you handled a gold coin?), and the quality of the fakes has improved tremendously. Counterfeiters, using modern technology, are able to produce fakes visually identical to genuine coins. Newspapers report of dealers, jewelers, and bankers all being fooled by good quality fakes.

How can an investor guard against buying fakes? By doing what the merchants of 100 years ago did-checking the authenticity of every gold coin bought. How do you check a coin? By using the same method that Gideon B. Smith's detector employed-weighing and measuring the coin against the issuing mint's specifications. Modern counterfeiters may have mastered the appearance of their fakes but the principle of density-the ratio of mass to volume-has not changed. Gold has a greater density than the common metals such as lead, brass, copper, and steel. This means that it is impossible to make a common metal fake (the only kind ever found) that is identical to a genuine coin in both weight and size.



No honest dealer wants to sell you a fake. But he can make a mistake. Don't be part of someone else's mistake-check every coin you buy. After all, who can look after you better than yourself?


First published in �The Financial Security Digest�, August/September 1983. P.O. Box 1928. Cocoa. FL 32922

"I started a Fisch thread a while back--I purchased the testers this fall (I got the Eagle and the Maple wallets)--they work perfectly...very handy when you are trolling the flea markets and such.

I showed it to my local dealer and he pulled out a Krugerrand he was stuck with that he knew was counterfeit (I cocked an eyebrow when he did that and he said he keeps it around for "comparison purposes"--besides, he sure as hell can't sell it!)

Anyhow...the detector worked like a charm--the coin couldn't pass all the tests."

http://www.kitcomm.com/showthread.ph...light=trolling



:36_3_16:

Re: Official Gold coin specification vs theoretical weight
 

I got the same one - plus a 2" larger variety - plus a OSCO Mini-mike.

No Phillies though - something told me not to buy these... :signs14::wink:

Even my Fisch Tools don't check for PHONEY Phillies.
:36_1_32v::36_1_32v:

Re: Official Gold coin specification vs theoretical weight
 

If the caliper measurment may be in error and we have absolutely no proof of the coins' weight, then this whole ordeal might be an exercise in pointlessness. Post a video of the coin being weighed were we can see that the scale is zeroed, not one that conveniently cuts out just before and after the coin is weighed.

edit: we would also have to see that the scale is calibrated properly.

Re: Official Gold coin specification vs theoretical weight
 

That video already has been posted:

<object width="425" height="344"><param name="movie" value="http://www.youtube.com/v/4F0UCyyYy8M&hl=en&fs=1&"></param><param name="allowFullScreen" value="true"></param><param name="allowscriptaccess" value="always"></param><embed src="http://www.youtube.com/v/4F0UCyyYy8M&hl=en&fs=1&" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="425" height="344"></embed></object>

Re: Official Gold coin specification vs theoretical weight
 

Hilarious. And if he could somehow do that you'd point out he could be faking the video some other way. We get it--you don't believe the claim. Good for you. However some of us are still interested in the possible fake and are willing to make the tentative assumption the guy isn't simply lying. So can you please shut up and let the investigation continue without getting yet another thread closed?

It seems to me the guy is doing the board a favor pointing out an apparent counterfeit coin and he gets treated very badly for it. If it was me I'd have told ya'll to fark off a long time ago and kept the information to myself.

Re: Official Gold coin specification vs theoretical weight
 

Dont tell me to shut up you jackass, I posted a legitimate concern that anyone with half a brain would consider. I never said I didn't believe the guy, but the conclusions are only as accurate as the data. Perhaps accuracy doesn't matter to you, it does to me.

Thanks to OJ for posting the video. We still need to see the scale calibrated, or at a bare minimum see another phill put on the same scale to make sure its weighing accurately.

Re: Official Gold coin specification vs theoretical weight
 

Please refrain from personal attacks, thanks.

Re: Official Gold coin specification vs theoretical weight
 

Only seeing the philli being measured as 1.65 mm of thickness (even as a off-rim measurement) should convince you that it's not a genuine one.

Otherwise, it would be underweight.

I encourage you to read back the original thread.

Re: Official Gold coin specification vs theoretical weight
 

RossL

I hope that I am not too late with this advice but you should leave your coins at home before you go fishing.

Re: Official Gold coin specification vs theoretical weight
 

Thats fine, but calibration of the scale is pretty darn important. Improper calibration doesn't mean that anyone is lying...but it does mean that the results are meaningless.

We know that -something- is amiss. That I'm sure everyone agrees. Measuring techniques that provide invalid data would qualify as amiss imho.

Re: Official Gold coin specification vs theoretical weight
 

Bingo. The rest is alotta sound & fury.
Calipers are cheap, a scale is cheap. Have one of of each when you buy a gold coin.

Re: Official Gold coin specification vs theoretical weight
 

The guy making the videos buys gold for a living, I assume he knows how to run an accurate scale. You can assume differently if you wish.

Also my comments were toward the history of nit-picky complaints from certain individuals that have added nothing beyond getting the previous thread closed (which might have been their intention from the start). It seems obvious to me these individuals think the OP is lying despite what they might say, but again you can assume differently if you wish.

Re: Official Gold coin specification vs theoretical weight
 

too late. I lost the Philharmonic in Alum Creek.

Re: Official Gold coin specification vs theoretical weight
 

Well that's just it. We are far enough beyond the rules of logic, that it is foolish to continue assuming anything.

It is precisely now, when the circumstances presented do not fit the norm, or even appear possible, that you begin questioning assumptions that you have made.

We have people questioning, in good faith mind you, whether a government mint is producing under carat coins. Its seems -very- reasonable that before we conclude that Pert Mint is cheating people, that we actually double check that our scale is accurate.

Re: Official Gold coin specification vs theoretical weight
 

I'm all for accurate scales and getting to the bottom of this. What I'm against is the crap that led to the previous thread being closed. Let's at least avoid that and I bet everyone will be satisfied.

Re: Official Gold coin specification vs theoretical weight
 

A friend actually flew to austria recently and purchased a sizable amount of phils direct from the mint. I have skimmed this thread to discover the origin of this purportedly fake coin but didn't see it. Do you think my friend could be holding under carat coins even though purchased direct from the austrian mint?
thanks

Re: Official Gold coin specification vs theoretical weight
 

What a crazy day this has been - but I think we have found the perfect spot for our third permanent location!

I have been out of town today but I do not believe the cops have picked up the coin (this just confirms to me that they are not taking our 'counterfeit' claim seriously). I will try to do another video tomorrow when I am back in the area, if the coin is still there.

To create a more convincing video, I will attempt to do the following without the camera losing sight of the coin:

1. weigh with the scale clearly showing 0 before and after, and 480gn when the coin is in the center of the scale
2. measure the dimensions of the coin with extra care taken to show variations of thickness depending on pressure applied by the calipers
3. acid test the coin

The last part should prove interesting, because some parts of the coin are very hard to get a sample from. That alone made me suspicious. And I remember that the sample I took from inside the coin dissolved under 22K acid within 20 seconds. But the acid test took quite a bit longer to dissolve when I got a sample from the outside of the untouched coin.

One poster (can't remember which thread) made a comment about the acid test being inaccurate. I could be wrong about this, but my understanding is that there is no premixed testing acid available which can melt pure gold.

Regardless, the premise that the acid test is off is certainly a possibility with karated jewelry, when 14K is often mistaken for 10K, or vice versa. This is done by inexperience, haste, and/or carelessness. And there are situations in which an acid test can incorrectly identify a sample as purer than it really is - stale acids, mixed acids, polluted applicator tips, residue of other metals or acids on the stone. You could even have a situation where some residue of a sample of lower purity is left on the stone, and causes 22K acid to discolor part of the "new" sample, leading you to believe that the sample is slightly lower than 22K. However, there is no possible situation known to me in which a 22K acid can dissolve a sample which is not .9167 or higher in purity.


Admittedly, my understanding of metals/alloys/chemistry is limited and I know a lot less about the subject than many who are participating in this thread. So maybe I am missing something when I say that I cannot find it physically possible to claim that even a variation as small as .05mm from the mint specs could exist, given that absolutely nothing other than .999 gold at 37mmX2mmcould weigh 480 grains.

Let's say the measurement was off by .15mm in the coin I showed. Even if the coin was 37mmx1.90mm thick, how could it weigh the exact same number of grains as a coin which measured 37mmX2mm and still have the same content?

Re: Official Gold coin specification vs theoretical weight
 

I got a Phil and took it down to Tom's Tech Cave to see what sort of measurement data came up.

This particular Phil was bought in 2006 from a major dealer so I have a lot of confidence in it.

Below I weighed it on a scale accurate to 1/100th gram. I have test weights down to .1 grain (1/70,000th lb), so the scale is accurate. The micrometer is calibrated in inches and is accurate to 10,000th inch and the caliper is good to 1/100th mm. The tools are professional level accurate.

Weight: 31.11 grams, pretty much spot flipping on

Diameter: 37.00 mm, again spot on

Here's where it gets to be a little more fun:

Thickness: depends on how and where you measure it.

Thickness measured with a caliper:
I used a Mitutoyo, a top end instrument. It has a definite "cut" in the jaws, top and bottom so it isn't reading the rim. Depending on how the coin was oriented, the reading was between 1.69 mm and 1.74 mm. I measured with the coin oriented in a lot of different ways and all measurements fell in this range. You may find a small (few thousandth) variation depending on die wear.

Thickness with a micrometer:
Understand that this micrometer, a Starret, is the "gold standard" of measuring instruments and is used by machinists to check very precise work.

There is no place on the coin where there is no raised surface on the coin on both sides large enough to get a measurement of the field. The measurements varied, according to placement, from the lowest observed .0639" (there is a vernier on the back side of the instrument) to a high of .0647". In metric these equate to 1.62 mm to 1.64 mm.

I interpret the difference between the caliper and micrometer readings to the probability that the caliper was resting on some minor high points compared to the much smaller contact area of the micrometer.

I think that the video showing a Phil at 1.65 mm thickness as measured by a caliper, concluding that it is a fake, is misinformed at best.

Re: Official Gold coin specification vs theoretical weight
 

It can't if the coins are cylinders. Without edges, fields and raised devices.

The coins aren't flat. The edge rim is 2mm, and as we determined earlier, the fields have to be less than 1.5mm thick.

Thus the theory has been proposed that dies could be created with less relief. That would allow a counterfeiter to have more mass and still keep the rim at 2mm and devices at 1.7mm.

To test this theory we would need to measure the thickness of the field on both a real coin and the fake.

Re: Official Gold coin specification vs theoretical weight
 

Thanks for the post, and interesting results.

Would you agree that a true .999 coin would have a consistent color throughout? Because the one we cut in half very clearly has two tones. The difference is glaringly obvious under the 16X loupe I used.

Even if for some reason they lied to me about the results of the assay of that very same coin, I saw with my own eyes the difference in color in the middle of the coin vs. the top and bottom.

I know you guys can't verify that - just sayin'. :biggrin:

Now the question is, why does everyone say that the coins should be 2mm thick? Where did they get these specs? The Mint? And why would the Mint's specs be incorrect?

This is an important question, because obviously, any of your thickness measurements would yield a weight dramatically different than 37.00mmX2.00mm of .999.

Re: Official Gold coin specification vs theoretical weight
 

Read my post, the coin isn't 2mm thick, that's the rim.

Re: Official Gold coin specification vs theoretical weight
 

OK, so you should be able to get a 2mm measurement as well, correct?

I guess one thing I could try is to see if the calipers are even touching our coin when they are at 2mm. I don't think they will be.

Re: Official Gold coin specification vs theoretical weight
 

The rim measurement is immaterial and variable.

Re: Official Gold coin specification vs theoretical weight
 

Variable, but within what tolerance?

I'm not trying to be obtuse, but I don't understand how, assuming the relief is always going to be the same for all real Philharmonics, the rim could be anything more than just slightly variable.

I think it would be interesting if we could get data on measurements of more real ones.

Re: Official Gold coin specification vs theoretical weight
 

Earlier in the thread we determined that a flat 37mm cylinder of 24K gold would be 1.48mm thick and weigh a troy ounce.

When that coin is struck by the dies under pressure metal flows into the dies. The result is the fields end up less than 1.48mm thick, the devices end up about 1.7 or 1.8mm thick and the rim ends up about 2mm.

depending on the dies, the actual measurments can vary a little bit. Several measurments have been made in this thread, and the results do vary.

In theory, if an alloyed coin planchet with 90% gold and 10% something else would start out about 10% thicker. So, the coin starts out 1.63mm thick, After it is struck with counterfeit low relief dies, the fields could end up 1.6mm, the devices 1.8mm and the rim still at 2mm.

That's just a theory. If a heavier metal was used to alloy with the gold, then the regular thickness could be attained.

Re: Official Gold coin specification vs theoretical weight
 

As posted before:

"Dear Sir,

If the 1 oz coin has a weight of only 18 karat gold, it is not a Gold Philarmonic coin. The Fine weight of the coin is desicive. (31,103 g)
The thickness is within the tolerance.



Best regards
Johann Hanslmaier
Direct Marketing

M�NZE �STERREICH AG
AM HEUMARKT 1 * 1031 WIEN * �STERREICH * POSTFACH 181
TELEFON +43 1 717 15-165 *
johann.hanslmaier@Austrian-Mint.at * www.austrian-mint.at

Firmenbuch Nr. FN 55543g, Handelsgericht Wien, UID-Nr.: ATU 37114706, ARA-Nr.: 7352, DVR: 0558826
-----Urspr�ngliche Nachricht-----
Von:
Gesendet: Sonntag, 19. Juli 2009 19:32
An: Abteilung Marketing
Betreff: 1 Oz Gold Philharmonic coin

I'd inquired as to the specifications, IF a 1.86mm coin thickness would be allowable?, apparently it is."

Re: Official Gold coin specification vs theoretical weight
 

So if 2mm is the thickness at the rim, yet in practice the thickness at the rim is variable, why does the mint put out a spec that has little or no practical use?

Sorry if this is a dumb question and I'm not understanding something, but why not use thickness at the field as the thickness spec?

Re: Official Gold coin specification vs theoretical weight
 

I also find it strange that the Austrian Mint publishes a 2mm standard thickness when accurate mesaurements are giving us the 1.6 range.

http://coins.coinupdate.com/austrian-gold-philharmonic/

Re: Official Gold coin specification vs theoretical weight
 

Kinda makes you wanta buy other types:

GAE
Krugs
Maples
Mexican

maybe?

:signs14::36_1_32v:

Re: Official Gold coin specification vs theoretical weight
 

The official Austrian mint specifications:

http://www.austrian-mint.com/philtechnischedaten?l=en

Face Value in Euro: 100,-

Purity: 999,9

Weight in g: 31,103

Diameter in mm: 37,0

Thickness in mm: 2,0

Re: Official Gold coin specification vs theoretical weight
 

That's very interesting.

The only measurement missing is the rim thickness, which is officially 2.0 mm, and has been measured accurately at 1.96mm by RossL.

Your coin seems to match the specs of 'TheSkeptic' coin.

Have you ever tried acid testing the coin? I understand that you want to keep the coin in good condition, but in theory, since it is 9999 fine, it shouldn't react at all to the testers, right?

Re: Official Gold coin specification vs theoretical weight
 

Has anybody measured the volume of the supposedly fake Phil and compared to the volume of a true 1 oz gold coin (Phil, Maple, AGE or whatever)?
A difference of about 4% should be quite observable...

As far as I know the outer part of a coin is different from the inside: the .99999 Maples say on the card that comes with the coins that only the inside of the coin has that purity. I assume the surface is hardened with a thin layer of non-.99999 gold.

Re: Official Gold coin specification vs theoretical weight
 

I was curious about that - if a coin (like the Maple Leaf, which looked so perfect I was shocked it was fake) could be .9999 yet still have room to contain an outer coating (even a thin flash coating) of impure gold? Is that possible?


OrangeJuice,

You can purchase testing stones so that you can rub samples from coins onto them instead of dropping acid directly onto the coin. It is very very rare for me to drop acid directly on any coin or jewelry.

There are a few different materials available for the stones, but Prostone is by far the smoothest, best, and easiest to read.

Re: Official Gold coin specification vs theoretical weight
 

1 Ounce gold 99999 (Maple leaf)
Certificate of authenticity
The Royal Canadian Mint attest that this coin meets the following definition for 99999 purity. Gold (Au) that is 99.999% pure is defined as having a sum of less than 10 parts per million of the following elements: Ag, Al, As, Bi, Cr, Cu, Fe, In, Mg, Mn, Ni, Pb, Pd, Pt, Sn, Si, Ti, Zn, and Zr. This refers to the bulk material below the coin surface.

---> Hence the coin surface is different from the bulk material below it.

Re: Official Gold coin specification vs theoretical weight
 

Very interesting. I have been wanting to learn more about this, and this is a good start.

Re: Official Gold coin specification vs theoretical weight
 

That's an interesting question. I assume the answer is that the mint assumes that the average consumer is limited to rulers or the like as a measuring device.

Just a little while ago I played with measuring a silver eagle. A SAE is advertised as having a thickness of 2.98 mm. The 2 decimal place accuracy level given is pretty funny because they have trouble keeping it within 1 decimal place. One coin I measured had rim thicknesses varying from 2.92mm to 3.07mm! The others were similar. Yeah 2.98 is close to an average. I measured the field thickness using the same methods as with the gold Phil. Using the calipers the thickness varied from 2.48mm-2.63mm depending on how the coin was rotated. The micrometer was able to fit in a place with no raised devices on either side and read 2.23mm.

I conclude that thickness is the least defined trait of a coin and its meaning is hazy at best and varies considerably. It is clear that the makers publish rim thickness as being the coin thickness, that is misleading at best.

BTW: the rim thickness on my Phil is 1.89 mm.

Skepic, I'm sure you will find it handy to know that an ounce of gold will contain 9.4 X 10^22 atoms of gold (+/- 8), just in case you have to count. :biggrin: