Different thickness silver Britainnias?

[Arian2020]

Hi everyone,

Just testing some recently purchased tubes of silver Britainnias and they all pass the weight test (31.19g-31.25g), pass the 99.9% purity test on the Sigma PMV and pass the magnet test and the width check (as they all fit into regular Britannia tubes and the STEALTH laser-cut MDF card). However, when having a stack of 25x 2017, 2021 and 2024 next to each other, the 2017 seems to be taller by as much as a whole coin, with the 2021 coming next and the 2024 the shortest. Any idea why these 2017 ones seem thicker? Raised rims? Any ideas would be much appreciated😶‍🌫️

[James32]

I'd just say thicker rims tbh

[Arian2020]

Thank you James, weird though - slight panic when you test them and when compared side-by-side you can just about tell the 2017 seem slightly thicker than the 2024 🤷🏽‍♂️

[James32]

13 minutes ago, Arian2020 said:

Thank you James, weird though - slight panic when you test them and when compared side-by-side you can just about tell the 2017 seem slightly thicker than the 2024 🤷🏽‍♂️

I remember seeing a thread years ago ( not sure where ) but buyer had Same issues with stacks of gold coins, long story short, the mint said it doesn't reveal thickness as it allows for variance. 

Edited March 15 by James32

[Pete]

Since silver has a fixed well specified density and the weight of 1 Troy ounce is precise, mathematically this means the volume is also fixed.
Coins are stamped from blanks rolled into sheets of specified thickness so the only explanation is variable rim thickness.
Maybe too much pressure during stamping squeezes a tiny bit of silver to the rim which then protrudes slightly.
Measuring centre thickness of coins using a micrometer is tricky due to surface cameo but you might detect a difference.
I've seen quite pronounced rims on some coins and also seen rims with a thin shard that peels off like swarf.
I wouldn't associate this to a specific year but specific batches.
 

[Arian2020]

Hi Pete, thank you that sounds very plausible too - at first I thought I was missing one from the stack and literally counted them 5x over! 🤪

[stackerp5]

I've posted something a couple years ago but in my case it was the different type of border on the edge. When the light hit both coins, because one border was a bit different it reflected the light differently. I thought it was a fake at first but I guess it's one of those things that just happen with mintages year-in/year-out.

[Arian2020]

Thank you stackerp5 - it is interesting to note all these differences and I am thankful to hear that others have also seen these types of discrepancies 👍🏽 

[Stacktastic]

I have a few 10ounce queens beasts that are not as thick all the way round. Pretty c**p.  

[Spyder]

This is the reason why the taller Britannia silver 1oz coin tubes can accommodate up to 26 coins.  

[bobski]

This may be a coincidence, but hear me out...

Physically the 17, 21, and 24 numbers themselves have a different volume of metal. I would expect a 2111 year Britannia to have a taller rim than all of the aforementioned (due to 111 taking up less volume than 024).

This in theory, would be because there's less of the blanks material used in the 'relief'. So with the coin field being the same depth as previous years, there would be 'spare' (extra) material pushed to the rim during the pressing.

It's a miniscule difference, but if you multiply that tiny difference by 25, you might notice?

 

All the best, Autistic engineer Bobski

 

[Shinus73]

7 hours ago, bobski said:

This may be a coincidence, but hear me out...

Physically the 17, 21, and 24 numbers themselves have a different volume of metal. I would expect a 2111 year Britannia to have a taller rim than all of the aforementioned (due to 111 taking up less volume than 024).

This in theory, would be because there's less of the blanks material used in the 'relief'. So with the coin field being the same depth as previous years, there would be 'spare' (extra) material pushed to the rim during the pressing.

It's a miniscule difference, but if you multiply that tiny difference by 25, you might notice?

 

All the best, Autistic engineer Bobski

 

If somebody has a stack of 2111 Britannias, I have other questions!

[bobski]

6 hours ago, Shinus73 said:

If somebody has a stack of 2111 Britannias, I have other questions!

It wasn’t a typo. It was the easiest way of explaining it. 

[SilverPlatinum]

On 15/03/2024 at 08:53, Arian2020 said:

Hi everyone,

Just testing some recently purchased tubes of silver Britainnias and they all pass the weight test (31.19g-31.25g), pass the 99.9% purity test on the Sigma PMV and pass the magnet test and the width check (as they all fit into regular Britannia tubes and the STEALTH laser-cut MDF card). However, when having a stack of 25x 2017, 2021 and 2024 next to each other, the 2017 seems to be taller by as much as a whole coin, with the 2021 coming next and the 2024 the shortest. Any idea why these 2017 ones seem thicker? Raised rims? Any ideas would be much appreciated😶‍🌫️

This is very interesting indeed.......💫

I would suspect the rims design but to know for sure why don't you get a digital caliper from Amazon and measure the rim and the diameter to see what it the difference between year 2017 and 2024!

Also please have those coins on a glass surface or direct on the wood table (without that green fabric) and see if you still have that difference in height!

 

 

[Arian2020]

Yeah good idea - I do have a set somewhere that I will dig out and measuring them on a known flat surface (rather than the green felt) seems like a logical step. Thanks again for the input 😎👍🏽

[bobski]

12 hours ago, Arian2020 said:

Yeah good idea - I do have a set somewhere that I will dig out and measuring them on a known flat surface (rather than the green felt) seems like a logical step. Thanks again for the input 😎👍🏽

I have some lovely Mitutoyo digital Vernier callipers, if you'd like to send me your samples. I can't guarantee you'll get the samples back though

[SilverPlatinum]

@Arian2020: Any update? 🙂

[Junior]

I know I’m late to the game on this one, but I have experienced this same thing with various Canadian Maple Leaf coins as well. Some years stack slightly higher. DNA (2014+) seem to have a minuscule height difference. If you trust the place you got them from and they pass the various tests you put them through, you should be good. 

[Arian2020]

Sorry everyoneI, have not had the time to do the checks yet (between work and play) - I’ll see if I can get to it over the next week or so 📐

[SilverPlatinum]

Hi @Arian2020.

Any update on this topic?  😀

[Arian2020]

Hello everyone! 😬 Apologies for the delay; you won’t believe how much I struggled to get  an LR44 battery for my callipers! 🙄

Anyway, re-did the stacking and tested measurements (Width and thickness) and the results are…inconclusive? 
 

Please see photos attached: the 2017 stack of 25x Britannias is still 1 whole coin to 1 1/2 coins taller than the 2024 stack, while the 2021 stack is somewhere in-between. The thickness of the 2021 coin, however, is 0.01 mm taller than the 2024 stack so you’d think overall that stack would be slightly taller (but this could be due to user error 😋). What does look likely, however is that the 2024 coins have a height of 0.03/0.04mm less than the other coins and counted up over 25x will result in a stack 0.75-1mm shorter than the others, which does seem not to be the case at the 2017 stack is at least 3mm taller than the 2024! 🤷🏽‍♂️ 

Anyway, anybody else want to play Scrooge McDuck and measure the size of your stacks, please be my guest and tell us if they are within the tolerance(s)?

 

Edited yesterday at 17:16 by Arian2020

[Arian2020]

More photos…Width 2017, 2021, 2024

 

Edited yesterday at 17:18 by Arian2020

[Arian2020]

More photos…Inside thickness 2017, 2021, 2024

 

 

 

Edited yesterday at 17:18 by Arian2020

[Arian2020]

More photos…Outside edge thickness 2017, 2021, 2024

[SilverPlatinum]

Thank you very much Arian2020 ! Appreciate all the efforts and time to resolve this mystery 😀.

So here what I understand from all the measurements you posted above:

Outside edge thickness:
2017:  25 coins x 3.07mm each = 76.75mm
2024: 25 coins x 2.91mm each = 72.75mm
Difference is: 4mm (which is about an additional 1.3 coin).

That makes since now that the 2017 stack is taller than the 2024 stack! We only need to confirm with anyone else who has 2017 Britannia if their edge thickness is 3.07mm too.