Fake gold coins?
 

I was reading another forum where someone was claiming to have purchased a tungsten alloy fake.

"Yes Happend to me last year !

Won a bid on E***Y
Seller n***yle
coin 1973 Bahama's $100 Gold .1609 oz
Payed $162.29

Coin did not pass messurement-test
coin did not pass weight-test

A local dealer then cut the coin in two .... turned out to be an alloy with Tungsten .
Despite this a claim with E***Y had no results
a claim with P**P*L had no results

Since then I DO NOT BUY anymore on E***Y ... nothing !!!
Since then I DO NOT USE P**P*L anymore ... never again !!!"

This got me thinking how it could be done.

Here is a site that sells tungsten powder which has a bulk density of 18.5 g/cc.

http://www.tungstenheavypowder.com/T...pds.html#Ultra

This powder is the same density as 22k gold.

http://www.ehow.com/how_4843884_iden...old-coins.html

Seems to me that someone could melt a small amount of 24k gold in with some tungsten powder and possibly come up with some alloy that was solid and malable enough to press a coin or blank that had the same density as 22k, something similar to sintering
( http://en.wikipedia.org/wiki/Sintering ).

You could either sleeve the blank with a thin layer 22k then heat and press it or coat/layer a pressed coin with 22k.

It would be a lot of work but it seems very possible with the companies that specialize in fake tungsten gold in China and possibly elsewhere.

http://www.tungsten-alloy.com/en/alloy11.htm
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Re: Fake gold coins?
 

In my wide contacts w/ dealers and collectors alike, I've never heard of anyone who has been stuck with a tungsten fake. Further I've never seen a scan of one on the internet.... just claims & hearsay so far.

Re: Fake gold coins?
 

Any pictures or other supporting documentation?

Re: Fake gold coins?
 

No pictures. Says he has them on DVD and used them when he tried to make a claim. I'm doubtful about the claim but it does seem possible and even likely in the future if gold goes nuts. I'll post a link if he ever posts pics.

Re: Fake gold coins?
 

He hasn't posted any thus far although he claims to have pics. The fact the guy states he lost his paypal claim clearly indicates he's lying as they rule in favor of the buyer 99% of the time ;).

Re: Fake gold coins?
 

If he has that much documentation, it takes about 5 seconds to upload a picture & post it. It's bullshit.

Sorry to say, but there's a lot of nutcases that fall into the PM hoarder category. I'm guessing this is off the kitco forum, hence the censory *****

Re: Fake gold coins?
 

Tungsten is difficult to work with, especially on a small scale. Nevertheless, I'm seeing a very sharp increase in fake gold, especially out of Europe.

Re: Fake gold coins?
 

you can get a lot of detail in a casting using the technique that is normally used for jewelry - lost wax investment casting, with either a centrifugal machine or a vacuum to suck the hot metal into the mold.

e.g. you can buy clear rubber at Tap Plastics. if you were to make a half cup of rubber, then put in a SAE, then add more rubber & make sure to get some rubber under the coin with no air bubbles ... etc. ... you'd have the mold for the wax that would be used to create a mold cavity very similar to an SAE..

the wax is usually suspended in a slurry similar to plaster of paris called investment. white sort of concrete-ish. that gets put in an oven at 1100 F to bake out the wax. so you're left with a pattern in the investment that is very similar to an SAE.

the difficulat part is, you have to get the metal to the cavity. normally for a ring you would use the edge, and have 1, 2, or 3 gates/sprues that when you look at them, maybe it makes more sense, like "oh, that's where the metal flows when it's hot".

the trick is filling the mold before the metal cools. having the mold be hot helps.

the mold material - the investment - is slightly porous. this is very important, since you have metal that is going into a cavity that has air in it and filling the cavity. so what happens to the air in the cavity ? it has to be pushed/ sucked.

hopefully the result is a nice smooth mirror surface, like on the pattern. in the case of jewelry you can spend a lot of time working on the master part from which the pattern is made.

if someone asked me to make a silver replica of an SAE, for example, normally i would run the sprues on the edges or on a convex surface. it is easier to clean up if the surface is rounded, like the outside of a ring.

of course, the reeding makes it more difficult to make the mold work - which may be part of the anti-counterfeit design of coins.

another thing that makes the task of making a replica difficult is shrinkage. normally the metal shrinks very slightly when it is cooling, about 1%. not a huge amount, but enough to be very troublesome if you are trying to make a metal part that matches a carved stone part.

so a replica that started from a 100% scale part will be slightly smaller on the molded replica. 1-2% smaller.

in order to circumvent that, counterfeiters that are using investment casting would have to build a master mold pattern that is 101.5% in size, approximately. they would use a process like CNC wire EDM and it would take a LOT of work.

same if they made a 100% scale die and used the same stamping technique as the mints used. the pattern is a lot of work.

please don't feel that i'm providing too much of a cookbook. to make a good replica, the replica-maker has to be a master machinist & mold person - with good vision. 5-10 years of training minimum.

(but if you want me to remove some info, let me know !)

anyway, like i said, one of the things i would look for is slightly undersize features and oddnesses around the reeding, in terms of trying to detect a counterfeit that may have been cast.

for a stamped counterfeit, i would just eyeball it next to a known good one. if a crook wire-EDM'ed a steel die using a CAD file from a 3D profile reading of a SAE, for example, the die will look pixelated after EDM'ing.

so then the pattern maker skills are required, which requires huge attention to detail & hundreds of hours.

normally i would say - normally people with those skills don't need to counterfeit stuff, they can get paid good doing legal machining. but the economy being as it is, and with criminal countries like ***** running around, the incentive for unemployed machinists to take a job doing die or pattern work for a counterfeiting job must be significant.

so the fact that these counterfeit parts are showing up is a sign that someone with considerable resources is hiring technical talent to expend 1000's of hours on what is basically a complex machining task.

bars with less detail are easier to counterfeit & stamp. i guess something like this
http://www.apmex.com/Resources/Catal...35629_slab.jpg

the buyer is in the position of "just trusting" the seller.

i wouldn't buy a bar like that off of someone on eBay, i'd buy it from a known trusted dealer. bars with that simple shape are much easier to fabricate, and therefore, to counterfeit.

do they ever have sessions at coin shows where they have real samples of counterfeits next to the real thing, so you can look at it with a magnifying glass etc. ? that would be fascinating.

Re: Fake gold coins?
 

Good post. Cast copies also usually have a porous, pock-marked, orange-peel finish. How do I know? I was stuck w/ one a few years ago. Funny thing was it weighed & sized correctly and was also a common-date.

Re: Fake gold coins?
 

Some good posts. Though some supporting documentation/pictures is what we are looking for. When gold reaches xxxxx per ounce ($10,000???) it more than likely will be worth it for people to start doing it. The temptation will be too great.

Re: Fake gold coins?
 

Does anyone know what temperature a Tungsten alloy would have to be heated to in order to cast into small molds as described above?

Re: Fake gold coins?
 

something doesn't smell right with the original post

If it didn't pass a weight test or a measurment test, then it wasn't a tungsten fake. probably some base metal that's flash plated with gold.

Why would a counterfeiter go to the trouble of working with tungsten if he wasn't going to make it pass a weight test and a measurment test?

Re: Fake gold coins?
 

From Wikipedia:

The chemical element with the highest melting point is tungsten, at 3683K (3410 �C, 6170 �F) making it excellent for use as filaments in light bulbs.

http://en.wikipedia.org/wiki/Melting_point

Re: Fake gold coins?
 

This is a pretty good article on counterfeit coins.

http://www.coinauthentication.co.uk/newsletter2.html

At the bottom it talks aboust cast sovereigns.

I also have a link to very very good photos on another forum of what is thought to be a cast sovereign but not sure if it's ok to post a link to the forum thread?

Re: Fake gold coins?
 

Here are the photos.

"So, that was it – for 8% below spot I got either a damaged but genuine coin, or a 22k fake"

Re: Fake gold coins?
 

My dealer has several books of fake gold coins. It is fascinating to look them over and try to visually detect the fake. With some it is literally impossible and other means absolutely must be employed. I am convinced that the OP is a phony; that is he is lying about it being a tungsten fake. The whole effing point of salting with tungsten is to achieve the same weight and dimensions as the real thing.

Re: Fake gold coins?
 

That hit me right off the bat too. The whole reason to work with such a difficult metal is to get the size and weight right.

Plus when I bought some fake Pandas, PayPal instantly got my money back.

The fake here is the story.

Re: Fake gold coins?
 

i have some silver jewelry pieces that i made that had small cavities. i tried to fill in using solder. that is a trick - there's many different kinds of solder.

how that would show up on a counterfeit silver or gold - sort of like "freckles". different color of gray or gold.

there's probably some chemicals that would be useful in this situation, e.g. affecting silver differently than a lead solder patch-up.

it does not look stamped. those little hairlines in front of his, well, hairline - as if the original die sculptor was sculpting a guy
with a few uncombed hairs.

the high-res pic really shows it up, which suggests another tool for detecting counterfeits - a good camera. if it's a digital
camera, then opening the pics up in Photoshop and really scrutinizing the image of the unknown coin.

anyway, that piece looks cast not stamped to me.

Re: Fake gold coins?
 

You are correct gunDriller this is thought to be a counterfeit casting. In the thread they refer to the raised areas in front of his eyes and below the neckline.