Sigma reliability reading small slabbed gold coin?

[arphethean]

Evening all,

I recently sold a 1/20oz slabbed gold 1996 panda. The buyer has tested it on his Sigma machine and it is reading way off true.

His photos show the Sigma reading and my photos show the coin.

To me everything looks right about the coin itself. Anything look wrong to you here?

I'm wondering if the Sigma is struggling with the small size of the coin and the thickness of the slab, but I haven't used a Sigma so not too sure.

PCGS checks out okay, though no photos https://www.pcgs.com/cert/17257992

[Cornishfarmer]

Where did you buy the coin from in the first place?    The slab doesn’t look like most pcgs slabs

[arphethean]

https://www.ebay.co.uk/itm/1996-LD-China-Panda-5-Five-Yuan-Gold-1-20oz-Coin-PCGS-MS69-Large-Date-/154660900776?nma=true&si=Eo4iGyc7XM4jM%2BuPoeRkpLcvF8w%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

[Mrpound]

very small denominations of gold in slabs…with the thinness of the gold and how thick the slab is with stale air between it I’ve found it has a hard time reading true for example 1/20th oz , 1/10th oz and 1/4 sovs it doesn’t like in slabs.

Edited November 20, 2021 by Mrpound

[Cornishfarmer]

34 minutes ago, arphethean said:

https://www.ebay.co.uk/itm/1996-LD-China-Panda-5-Five-Yuan-Gold-1-20oz-Coin-PCGS-MS69-Large-Date-/154660900776?nma=true&si=Eo4iGyc7XM4jM%2BuPoeRkpLcvF8w%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

Should be legit from the London coin company.       Haven’t heard about them for years but about 5 years ago they didn’t have the best reputation on here

[arphethean]

Thanks for your responses. I would be very surprised if it were fake, both  because the details to me appear genuine, and as you say I'd expect things from LCC to be genuine with 26k feedback etc.

I have of course offered a refund to the buyer but I think I will maybe approach LCC to see what their opinoin would be 

[Cornishfarmer]

24 minutes ago, arphethean said:

Thanks for your responses. I would be very surprised if it were fake, both  because the details to me appear genuine, and as you say I'd expect things from LCC to be genuine with 26k feedback etc.

I have of course offered a refund to the buyer but I think I will maybe approach LCC to see what their opinoin would be 

😂😂😂 you might see why they got so much stick a few years ago.           Could have got some new reps now so might be better now

[SilverStorm]

There was a YouTube video posted by Silver Seeker several days ago when he tested his 999 fine silver bar with a Sigma.  The arrow showed the silver as being out of bounds.  He assumed the silver was fake and proceeded to do a specific gravity test and acid test.  He even drilled a hole into his silver bar to look for the fake insert.  He did not find any.  When he retested his silver bar on a lower setting (97%?), it was in bound. So his testing concluded that his silver bar is indeed silver, just not 999 fine.

With regards to your Panda, it’s possible that it’s not 999 fine gold.   It’s most likely is “pure” gold, just not three nines fine.  And the Sigma will throw an out of bounds error because of that.   

I recommend that you ask the buyer to retest the Panda at next lower setting and see where that comes at.   If it comes in OK, it means the Chinese mint did not provide the exact quality of gold that was stamped on the coin.  ie stamped as 999 fine gold but is not actual 999 fine, maybe 995 fine gold.

Edited November 22, 2021 by SilverStorm

[mr1030]

Also worth considering,  I think I remember reading in the Sigma manual that the main sensors are not good at reading very small or thin pieces of gold.  For those they suggest using the small wand on the gold piece and placing the calibration disc that came with the machine on the opposite side of the coin/bar.  I know that isn't feasible in that yours is slabbed.  The point is the main sensor isn't supposed to be used with items that small or thin.  Might be a good idea to contact Sigma support and ask them the best way to test that item.

[arphethean]

Thanks all very much for sharing your know how. 

I'm not concerned about its Authenticity myself but will make sure the buyer is happy. 

Cheers