Shocking results with Sigma Major failure

[Spyder]

Replaced earlier video with a zip file to make it quicker to watch.  Personally I use VLC player to watch.

Edited July 21, 2023 by Spyder

[JohnA1]

11 hours ago, Spyder said:

Glad that this thread is still being used.

I have the recorded the fake bar with the sigma. Ignore the scales as I had the wrong settings and the battery needed replacement. The bar again tricked the sigma. Now if I was to just take photos and try to sell the bar to a novice and tell them do not remove from blister pack, they may just do that. Locked it away and one day will find that it is worthless.

Roy has got the correct idea, maybe stick to very tiny bars as they be too thin to try and plate.

 

Replaced the video with a zip file as it was taking too long to watch with buffering all the time

I use VLC player to watch. 

 

20230717_191640_1_1.7z 262.33 MB · 1 download

Watched the video.

First of all, according to the instructions this version of Sigma (only checks for plating) cannot check this bar on the main sensor, because it is too small (doesn't fully cover the circle).

You'd need to use a wand for it.

I can see why you are worried, I'd be worried as well with this version of Sigma and a gold bar in a blister pack. The thick plastic makes a difficult measurement even worse (maybe on purpose?)

If you tried the wands on the naked bar and still got false positives, I'd be alarmed.

If you are conviced that it is fake, cut the bar so we can see if it is plated and how thick the plating is. If it is a wrap, then remember the wands only go a fraction of a mm deep.

 

The new sigma wouldn't flinch since it measures through the whole bar (calculating thickness) - plus the dimension test would show immediately that it is too big for that weight.

 

 

Edited July 21, 2023 by JohnA1

[Spyder]

25 minutes ago, JohnA1 said:

Watched the video.

First of all, according to the instructions this version of Sigma (only checks for plating) cannot check this bar on the main sensor, because it is too small (doesn't fully cover the circle).

You'd need to use a wand for it.

I can see why you are worried, I'd be worried as well with this version of Sigma and a gold bar in a blister pack. The thick plastic makes a difficult measurement even worse (maybe on purpose?)

If you tried the wands on the naked bar and still got false positives, I'd be alarmed.

If you are conviced that it is fake, cut the bar so we can see if it is plated and how thick the plating is. If it is a wrap, then remember the wands only go a fraction of a mm deep.

 

The new sigma wouldn't flinch since it measures through the whole bar (calculating thickness) - plus the dimension test would show immediately that it is too big for that weight.

 

 

Will do a new video with wands as they too get false readings.  This thread was a warning to members not to just rely on a photo showing the bar on a Sigma machine with correct reading showing in between the lines.

[Nick69]

Did you test it on measurement mode on the sig pmv?..just an idea.

[paulmerton]

On 17/07/2023 at 16:52, JohnA1 said:

Wow, just saw this thread.

I haven't got this version of PMV, but I think that none of the readings appearing here are valid - because the cursor is not black.

I suspect that the difference in the cursor colour is the instrument warning that the reading is not correct.

Now if the cursor were black and between the brackets, then you'd have reason to question the accuracy, as long as the setting were on the correct coin type (yet another gotcha!)

Even then, the PMV Original only checks for plating, it doesn't check through the whole of the coin. Only the PMV Pro does that, along with specific gravity testing.

 

Here's the definitive answer.

[JohnA1]

Nice one, good to have a definitive answer.

it is still important to stress that the whole circle needs to be covered for a reliable reading (whether the coin/bar is plated or not)

[JohnA1]

Speaking of the Sigma 'classic' being misleading on its own (we know to always use alternative methods no matter what),  go to 2min 10sec of this video.

He says a lead-based coin (according to their XRF) tested 'pure' silver on sigma classic.  Oooops 😕

I suspect there was a lead core, Sigma only tests a certain number of microns deep - but doesn't the XRF also only go skin-deep?🧐

Interesting, eh

 

At 11:45 he tells a story that makes you think what a problem plated c**p can be if the source is dodgy

Edited August 3, 2023 by JohnA1

[paulmerton]

24 minutes ago, JohnA1 said:

Speaking of the Sigma 'classic' being misleading on its own (we know to always use alternative methods no matter what),  go to 2min 10sec of this video.

He says a lead-based coin (according to their XRF) tested 'pure' silver on sigma classic.  Oooops 😕

I suspect there was a lead core, Sigma only tests a certain number of microns deep - but doesn't the XRF also only go skin-deep?🧐

Interesting, eh

 

At 11:45 he tells a story that makes you think what a problem plated c**p can be if the source is dodgy

Plating has hardly any effect on the classic readings.

The classic Sigma goes a lot deeper than you seem to think it does. It depends on the resistivity of the test subject, but for example the main sensor will detect things like tungsten through an entire millimetre of 22k gold. The bullion wand will go ever deeper.

[JohnA1]

 

[paulmerton]

2 minutes ago, JohnA1 said:

 

See? Gold plating is only a few microns or less thick, and all of these depths are significantly larger.

Incidentally the GoT depth for 24k gold is lower than that for 22k due to the resistivity, which is why it works even deeper for things like sovereigns.

 

[JohnA1]

Yeah, 1000 microns=1mm

Sigma classic catches plating - which is the most widespread issue.

I think it is the absolute minimum of the 'advanced' tools for a stacker, especially if they handle gold (scales, calipers and magnets are essentials of course)

 

Edited August 3, 2023 by JohnA1

[JohnA1]

Worth a look I think, one cannot be too careful nowadays..

[Nick69]

4 hours ago, JohnA1 said:

Worth a look I think, one cannot be too careful nowadays..

Not a lot of people use measurement mode on the pmv original, it gives specific figures for any coins/bars. It's always worth a mag, weigh and cali check as standard.