Home made coin tester

[Connor]

I'm just wondering if these are quite common? It's a homemade stack of neodymium magnets set at an angle. Basically a slide for your silver. Thinking about buying one, what's everyone's thoughts?

[Fishface220]

I have one. Brilliant bit of kit. 

[silenceissilver]

I have seen something similar on the Salviate Metal Youtube channel. It seemed to work quite well. I have used simple magnet tests without such a construction for gold and silver and no problem for silver but because the effect with gold is quite small, it can be a pain in the butt to do a simple magnet test for gold. Thus, I think these home made metal testers are very likely to prove to be very helpful for gold coins, possibly also for fractional silver coins. For one ounce silver coins you can use it too but it's not really necessary there, as the effect is big enough just with a simple neodym magnet

[AgD]

13 minutes ago, silenceissilver said:

I have seen something similar on the Salviate Metal Youtube channel. It seemed to work quite well. I have used simple magnet tests without such a construction for gold and silver and no problem for silver but because the effect with gold is quite small, it can be a pain in the butt to do a simple magnet test for gold. Thus, I think these home made metal testers are very likely to prove to be very helpful for gold coins, possibly also for fractional silver coins. For one ounce silver coins you can use it too but it's not really necessary there, as the effect is big enough just with a simple neodym magnet

The one on sal's channel would be from CCT he is on Instagram and YouTube been a friend of mine for years now and he is UK based as well and he hand makes all the slides and ships them worldwide.

[Connor]

15 minutes ago, AgD said:

The one on sal's channel would be from CCT he is on Instagram and YouTube been a friend of mine for years now and he is UK based as well and he hand makes all the slides and ships them worldwide.

He's not from Sheffield by any chance?

[Pete]

Weight, diameter & thickness and if necessary specific gravity test to verify genuine purity of PMs.
If you are wanting to use a Nd magnet then the small button ones are cheap and work fine.
My worry sliding metal over metal - pure silver is soft - Nd magnet is hard - result is scuffing or scratches !!!

[AgD]

7 hours ago, Connor said:

He's not from Sheffield by any chance?

Not that far up. 👍

[Connor]

44 minutes ago, Pete said:

Weight, diameter & thickness and if necessary specific gravity test to verify genuine purity of PMs.
If you are wanting to use a Nd magnet then the small button ones are cheap and work fine.
My worry sliding metal over metal - pure silver is soft - Nd magnet is hard - result is scuffing or scratches !!!

That's a fair point

[silenceissilver]

44 minutes ago, Pete said:

Weight, diameter & thickness and if necessary specific gravity test to verify genuine purity of PMs.
If you are wanting to use a Nd magnet then the small button ones are cheap and work fine.
My worry sliding metal over metal - pure silver is soft - Nd magnet is hard - result is scuffing or scratches !!!

Good point. I think the model that Salviate Metal used, has felt over the magnets in order to avoid scratches.

[AgD]

1 hour ago, silenceissilver said:

Good point. I think the model that Salviate Metal used, has felt over the magnets in order to avoid scratches.

This will be the type he uses 

[47Ag79Au78Pt]

Hi,  I do hope you don't mind me pitching in here, but there are lots of videos on YouTube on "The Lenz Effect."  Click here. If you slide different metals of the same mass down exactly the same angle slide then, what you'll be testing is the relative conductivity of the different metals.  The more conductive metals like silver, copper, aluminium and gold, will move more slowly. To be honest I've only ever demonstrated this to a room of bored-looking 15 year olds using a strong neodymium magnet and a copper pipe.  I've never done it with a flat magnetic surface like the one in the video, but this is the physics behind MagLev trains or linear motors in general.

A magnet slide would be useful for sorting through a large pile of Nickels and Dimes so that you can quickly separate the high and low silver content coins, but if you're trying to detect a forgery where someone has alloyed different amounts of copper into silver then the magnet slide test would be quite difficult to verify, because they're both highly conductive metals, so they both would slide quite slowly.

Also you would need a 'control' coin to compare against, and the quickest way you'd tell the difference between a control (genuine) coin and a fake would be a difference in weight or volume/size and density. This video shows the slide in action and the bloke does a nice comparison with a tungsten round.  But it's definitely not an absolute science.  There's a certain amount of guestimation needed, and this wouldn't reveal a sophisticated fake.  

You could, theoretically come up against a fake alloy, where someone has smelted a pile of copper into the silver and then JUST the right amount of lead to obtain a very similar density to .999 silver, but the conductivity of these two coins would be quite different.  So long as you have a control coin, then this is what a Sigma machine will tell apart.  Interestingly, the Sigma website has a page on methods of detecting counterfeit coins and their appraisal of the magnetic coin slide is "This method is simple and inexpensive, but only reveals very cheap and low-quality counterfeits." Sigma website click here.

What I'd love to know is has anyone faked a popular coin like a Sovereign or a QB with a different alloy or a tungsten core?  I would imagine it would be incredibly difficult compared to a poured bar of silver.

Anyway, I hope that's a helpful contribution to the discussion.