Difference in weight in same coin series

[zittergie]

Hi,

I wanted to test some of my digital scales and I wondered what is the tolerance in weight for specific coins.  I have weighed 3 types of 1oz coins and I found out that the Canadian Maple Leaf is very strict in weight.

 

Difference between lowest and highest weight

Canadian Maple Leaf 2017:  0,05 gr.  (on 50 coins)
American Silver Eagle 2014:  0,26 gr.  (on 10 coins - with thanks to @Jester)
Australian Kangaroo 2017:  0,30 gr.  (on 50 coins)

I have taken the weight of the most and least heavy coin a few times, with 2 different types of scales.
I also found out that the Maple Leaf is closest to 1oz than the other 2, where the ASE is the most heavy coin.  Could this be to the fact that this coin is .999 instead of .9999

[kimchi]

I noticed this when I first started out with Kooks, and while the dealer told me there is a 'minimum' weight and it can vary across silver (and that mints are much more precise for gold for obvious reasons!) I emailed the Perth Mint to be sure, and they basically gave me the same answer.

[Gav]

I also did this experiment and got interesting results. The new design of the maple leaf had a lower standard deviation than the older version. The average weight of the 2012 Maples had a weight of 1.008 toz and varied between 1.001 to 1.013 toz.

While the average weight of the 2017 Maples had a weight of 1.001 toz and varied between 1.001 to 1.003 toz

[Cacc]

The more 9s, the closer it will be to the coin weighing in at exactly 1oz. The 9s are the purity in percent, so if something is 99.99% then only 0.01% is a different alloy which adds to the weight. All 1oz coins have 1oz of silver in them, but then another alloy added to it. This can be seen more in gold coins where the Maple Leaf is 9999 and the American Eagle is 9167, so the American Eagle will weight more over all because 8.33% of the coin is an alloy other than gold but there is still exactly 1oz of gold in the coin. Get a coin that is 99999 and it will be even closer to the whole coin weighing exactly 1oz.

[sovereignsteve]

I think there are two discussions taking place here;

the target weight of the coin, dependent on the amount of pure metal in the alloy, and,
how consistently the mint can reproduce the target weight in each individual coin, ie the precision.

 

[kimchi]

32 minutes ago, sovereignsteve said:

I think there are two discussions taking place here;

the target weight of the coin, dependent on the amount of pure metal in the alloy, and,
how consistently the mint can reproduce the target weight in each individual coin, ie the precision.

 

Absolutely agreed (for whatever it's worth - I'm still a grasshopper!).

From my reply from Perth Mint, I am guessing mints aren't that precise about silver blanks as long as they meet the minimum 999(9) and weight for 'treadmill' bullion. As long as they get the metal in sufficient raw state purity, what's 0.03 to them on a coin compared to mixing in alloy and then verifying each batch, and then having to melt and try to purify further any 'bad batches' and then restrike? Makes no economic sense to me.

Nothing is 100% pure (hence no 100% coins). 9999 silver they can be slightly surer that the blanks can be closer to the minimum target and still contain 1 Oz of Silver. Gold they all need to be more careful on, because slight fluctuations matter an awful lot more at that price.

There will obviously be different quality controls and levels of sophistication of equipment between mints, hence the differences in variation.

Sterling Silver or 22ct gold is a different kettle of fish because then they do (would have to?) mix alloys.