Unusual Sigma Metalytics Readings

[Organics]

I purchased my Sigma Metalytics PMV original in December 2021. I haven't used it many times, as 99% of the time I buy my bullion from a reputable dealer. However yesterday I met a someone to purchase some gold sovereign coins. I thought this would be a great time to use my PMV to test them before paying. 

As you can see from the pictures attached I tested the 22kt Sovereign and it came up within the brackets as I would expect. However here's where it gets confusing. The collector had never seen a PMV before and asked me how it works and what happens if it's not gold. As I was explaining to him I put a 20 cent coin (Euro) on the scale, expecting to see an off the chart arrow. To my disbelief it came up as 22kt gold. I thought this was an error. So I switched off the machine and tried again. Again the same thing happen. The collector looked at me for an explanation but I didn't have one. I then tried a 50 cent coin and couldn't believe when the same thing happened. Now clearly these coins are not 22kt gold and so would like an explanation of what is going on. Luckily for me I had some other things with me to test the coins weight, dimensions, magnet, etc, as otherwise I didn't feel confident in the PMV readings. 
 

I’ve reached out to Sigma and in their defence they responded straight away. However they are saying that this situation is well known and in the manual and FAQ’s on their website. They say in their response “A sample that passes the resistivity test can ONLY be considered genuine if it is also confirmed to be the right density. 
 

They told me to test again using the wand as the samples were too small. So I did. Both the 20 cent and 50 cent coins passed again. 
 

It’s a shame they don’t make that very clear before someone makes a €1000 investment, based on what they say on the PMV sales page.

 

“Keep Your Collection Safe

The PMV Original is ideal for private investors and collectors looking to verify their coins and bars. The Original lets you verify your existing collection and continue to grow your investments with confidence.”

Clearly after these readings I’m not building as confidently as I thought I was and will have to recheck some other coins I purchased. 
 

I’m curious to know how many of you knew about this, and still went ahead and made the purchase.  

 

Am I making more of this than I should 🤔
 

Best wishes.   

[Organics]

UPDATE!!!

Just received this from Sigma

“Hi, Based on your feedback, we have added an attention section to the product page of the PMV Original. I hope that helps future customers understand the details of the PMV Original prior to making their purchase”

Fair play to them. Just wished they had been more transparent sooner. I guess not many buyers are testing 20 and 50 cent coins! 

[Organics]

What the new section on the product page reads:

ATTENTION

The PMV Original is not an all-in-one testing device. It is critically important to test the density of your samples in addition to testing the resistivity. The PMV Original only tests the resistivity of the sample. A sample can only be considered genuine if both the resistivity and density are correct. The PMV PRO series does test both density and resistivity, but when testing with the PMV Original, the user must test density separately on their own.

[ArgentSmith]

On its own the Sigma is diabolical. It's a great addition coupled with a SG test but will fail to detect gold clad tungsten. This is where an additional ultra sound or resonance (ping test) is bullet proof as far as I know. 

[Organics]

4 minutes ago, ArgentSmith said:

On its own the Sigma is diabolical. It's a great addition coupled with a SG test but will fail to detect gold clad tungsten. This is where an additional ultra sound or resonance (ping test) is bullet proof as far as I know. 

Had no idea. Starting to wonder if I did the right thing with €1000 🤦‍♂️

[ArgentSmith]

1 minute ago, Organics said:

Had no idea. Starting to wonder if I did the right thing with €1000 🤦‍♂️

It depends what you are testing, 999 fine has far less tolerance than 22ct or sterling. Say you are testing a sovereign I would say old school scales with a slot is the best single test. Highly unlikely to be tungsten core and if it was due to its small size the sigma would likely detect it. I think it's a great tool if you understand its limitations.

[modofantasma]

49 minutes ago, Organics said:

I purchased my Sigma Metalytics PMV original in December 2021. I haven't used it many times, as 99% of the time I buy my bullion from a reputable dealer. However yesterday I met a someone to purchase some gold sovereign coins. I thought this would be a great time to use my PMV to test them before paying. 

As you can see from the pictures attached I tested the 22kt Sovereign and it came up within the brackets as I would expect. However here's where it gets confusing. The collector had never seen a PMV before and asked me how it works and what happens if it's not gold. As I was explaining to him I put a 20 cent coin (Euro) on the scale, expecting to see an off the chart arrow. To my disbelief it came up as 22kt gold. I thought this was an error. So I switched off the machine and tried again. Again the same thing happen. The collector looked at me for an explanation but I didn't have one. I then tried a 50 cent coin and couldn't believe when the same thing happened. Now clearly these coins are not 22kt gold and so would like an explanation of what is going on. Luckily for me I had some other things with me to test the coins weight, dimensions, magnet, etc, as otherwise I didn't feel confident in the PMV readings. 
 

I’ve reached out to Sigma and in their defence they responded straight away. However they are saying that this situation is well known and in the manual and FAQ’s on their website. They say in their response “A sample that passes the resistivity test can ONLY be considered genuine if it is also confirmed to be the right density. 
 

They told me to test again using the wand as the samples were too small. So I did. Both the 20 cent and 50 cent coins passed again. 
 

It’s a shame they don’t make that very clear before someone makes a €1000 investment, based on what they say on the PMV sales page.

 

“Keep Your Collection Safe

The PMV Original is ideal for private investors and collectors looking to verify their coins and bars. The Original lets you verify your existing collection and continue to grow your investments with confidence.”

Clearly after these readings I’m not building as confidently as I thought I was and will have to recheck some other coins I purchased. 
 

I’m curious to know how many of you knew about this, and still went ahead and made the purchase.  

 

Am I making more of this than I should 🤔
 

Best wishes.   

From my understanding if you look at the table with alloys, thickness and dimensions in the instructions you need to use the wand and calibration disk beneath the coin for a sovereign. As @ArgentSmith suggests it would be unwise to rely on one single test.

[paulmerton]

I've said it on here many times before, but all the basic sigma does is tell you if the resistivity of the test subject matches the resistivity of the metal you're hoping it to be.

You can make non-precious alloys that have the same resistivity as pure gold for instance. That doesn't mean the test subject is pure gold and it shouldn't be interpreted that way. However, if the resistivity doesn't match, then you know it's not gold - that's where the true usefulness lies.

I knew this by reading the manuals beforehand and still decided to buy one. Coupled with a set of sovereign scales (which effectively check both the weight and the density are correct) and some common sense I think it's a useful tool.

[paulmerton]

16 minutes ago, ArgentSmith said:

It depends what you are testing, 999 fine has far less tolerance than 22ct or sterling. Say you are testing a sovereign I would say old school scales with a slot is the best single test. Highly unlikely to be tungsten core and if it was due to its small size the sigma would likely detect it. I think it's a great tool if you understand its limitations.

Another interesting limitation is that pure copper falls within range on the 999 silver setting. It doesn't on 9999 though.

[ArgentSmith]

Two tests same coin 😆

[ArgentSmith]

2 minutes ago, paulmerton said:

Another interesting limitation is that pure copper falls within range on the 999 silver setting. It doesn't on 9999 though.

I didn't know that. I always use 9999 since 999 will get close. I would have thought 999 copper would have been far enough away from 999 silver though.

A magnet slide test wont tell the difference between Copper and Silver either.

[paulmerton]

34 minutes ago, ArgentSmith said:

I didn't know that. I always use 9999 since 999 will get close. I would have thought 999 copper would have been far enough away from 999 silver though.

A magnet slide test wont tell the difference between Copper and Silver either.

Indeed. Silver-plated copper is a fiend. The density is so close, as is the resistivity and it's behaviour under a magnet.

[Organics]

17 hours ago, ArgentSmith said:

It depends what you are testing, 999 fine has far less tolerance than 22ct or sterling. Say you are testing a sovereign I would say old school scales with a slot is the best single test. Highly unlikely to be tungsten core and if it was due to its small size the sigma would likely detect it. I think it's a great tool if you understand its limitations.

Thank you. I’ll have a look for one of those. At least Sigma have changed their product page now with the new information 

[Organics]

17 hours ago, paulmerton said:

Another interesting limitation is that pure copper falls within range on the 999 silver setting. It doesn't on 9999 though.

Goodness. Had no idea! Thanks for sharing. Just bought a ping tester kit, for another level of security. 

[Organics]

18 hours ago, ArgentSmith said:

It depends what you are testing, 999 fine has far less tolerance than 22ct or sterling. Say you are testing a sovereign I would say old school scales with a slot is the best single test. Highly unlikely to be tungsten core and if it was due to its small size the sigma would likely detect it. I think it's a great tool if you understand its limitations.

I’ve had a look at those vintage scales with the slot in the middle. I can’t seem to see any instructions on how to use them. If the coin goes through the slot, does that mean it’s ok? 

[ArgentSmith]

2 minutes ago, Organics said:

I’ve had a look at those vintage scales with the slot in the middle. I can’t seem to see any instructions on how to use them. If the coin goes through the slot, does that mean it’s ok? 

If it's the right size and weight it's passed what is in effect a specific gravity test.

[paulmerton]

Just now, Organics said:

I’ve had a look at those vintage scales with the slot in the middle. I can’t seem to see any instructions on how to use them. If the coin goes through the slot, does that mean it’s ok? 

If it fits through the slot, fits in the tray, and tips the scales, it's probably okay.

Most metals used in fake coins aren't dense enough to tick all three boxes. Tungsten or platinum alloyed fakes could pull it off, but that's where extra things like eyeballs and sigmas would tip the balance in your favour (hoho).

[Organics]

18 minutes ago, paulmerton said:

If it fits through the slot, fits in the tray, and tips the scales, it's probably okay.

Most metals used in fake coins aren't dense enough to tick all three boxes. Tungsten or platinum alloyed fakes could pull it off, but that's where extra things like eyeballs and sigmas would tip the balance in your favour (hoho).

Thank you so much 🙏

19 minutes ago, ArgentSmith said:

If it's the right size and weight it's passed what is in effect a specific gravity test.

Thank you again 🙏

[Minted]

Found this thread a very interesting read myself.  Can anyone justify why the price of the Sigma is so high, particularly given that it only does one test and is far from 'fool-proof'?

I'd be interested to know how much the main electronic component in it costs?

Edited April 9, 2023 by Minted

[universalcurrency]

 

On 09/04/2023 at 14:29, Minted said:

Found this thread a very interesting read myself.  Can anyone justify why the price of the Sigma is so high, particularly given that it only does one test and is far from 'fool-proof'?

I'd be interested to know how much the main electronic component in it costs?

I would imagine the bulk of the price is US labour rates. Personally I think the US price for the original & wands is acceptable although I probably wouldn't pay the UK price most retailers are charging.

[Zeuk]

On 09/04/2023 at 16:29, Minted said:

Found this thread a very interesting read myself.  Can anyone justify why the price of the Sigma is so high, particularly given that it only does one test and is far from 'fool-proof'?

I'd be interested to know how much the main electronic component in it costs?

Partly manufacturing cost, partly  because there’s a market they can charge this price point to and be viable.  

[paulmerton]

4 minutes ago, universalcurrency said:

 

I would imagine the bulk of the price is US labour rates. Personally I think the US price for the original & wands is acceptable although I probably wouldn't pay the UK price most retailers are charging.

Anyone willing to do a tear-down to see what's inside?

There's no way the construction labour and components cost anywhere near the selling price. The bulk of it is surely for R&D, which has already been done now so they must be making huge profits per unit.

[kimchi]

On 09/04/2023 at 14:29, Minted said:

Found this thread a very interesting read myself.  Can anyone justify why the price of the Sigma is so high, particularly given that it only does one test and is far from 'fool-proof'?

I'd be interested to know how much the main electronic component in it costs?

I believe it's a small(ish) business that is proudly USA made/assembled, so it simply can't and is not trying to compete with Asian manufacturers. I know another company (producing a completely different kind of scientific product) based in China who import some essential parts from the US because they say the quality is top notch and not replicated.

On that note, is there a Chinese/etc version?

I've had cause to contact Sigma regarding my unit, and so far their customer service has seemed very honourable

17 minutes ago, paulmerton said:

Anyone willing to do a tear-down to see what's inside?

That would be interesting!

<edit> Weird to see folk posting in this thread (even with photos) of how it tells you NOT to use the device in the manual!

Edited April 12, 2023 by kimchi

[ArgentSmith]

14 minutes ago, paulmerton said:

Anyone willing to do a tear-down to see what's inside?

There's no way the construction labour and components cost anywhere near the selling price. The bulk of it is surely for R&D, which has already been done now so they must be making huge profits per unit.

The Chinese could probably ship these for £10 each, without "R&D" costs 😆

Glad to have one though, very useful if you understand its limitations  and like anything in a niche market its never gonna be a bargain.

Edited April 12, 2023 by ArgentSmith

[Zeuk]

18 minutes ago, ArgentSmith said:

The Chinese could probably ship these for £10 each, without "R&D" costs 😆

Glad to have one though, very useful if you understand its limitations  and like anything in a niche market its never gonna be a bargain.

Yep, decent quality product with good utility.  No doubt China could copy easily in an unethical way.  The price point isn’t unreasonable imo, barriers to entry for the average joe will be too high and they can’t shift high volumes given the niche, so payback and sustaining employees can’t be that easy