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I Have A Puzzle To Solve For A B-Day Present. Please. Same Size, Different Thickness?

 
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Author Previous TopicReplies: 9 / Views: 370Next Topic  
Valued Member
United States
74 Posts
 Posted 11/30/2021  7:34 pm Show Profile   Bookmark this topic Add jaberwoke to your friends list Get a Link to this Message
Hello all!

I have a puzzel for you all. Here's the story:

I found a B-day gift for my daughter who's "nom de plume"/pseudonym for her email has always been "phoenixdraco". It's the 2017 Australian Phoenix Dragon 1 oz from the Perth Mint. What a find for my purpose as a gift, don't you think?!

I thought it would be cool to get a coin bezel also if she'd like to wear it as a necklace. But... I ran into a problem. And so the puzzel begins. I can't find a bezel to fit.

Here are the dimensions of the AU coin:

Australian 2017 Dragon & Phoenix 1oz Silver Bullion Coin:

Precious Metal Content (troy oz): 1.000
Fineness: 99.99% purity
Weight (g): 31.135
Diameter (mm): 40.600
Thickness (mm): 4.000
Edge: serrated


Same diameter as an American Eagle 1 Oz., right? But look at the thickness as compared the Eagle:


American Silver Eagle:

Mass 31.103 g (1.00 troy oz)
Diameter 40.6 mm (1.598 in)
Thickness 2.98 mm (0.1173 in)
Edge Reeded
Composition 99.9% Ag


The puzzel:

Same weight, same purity, same diameter but a 1.2 mm larger thickness? how is that possible?

Buehler? Buehler?

What am I missing?
Edited by jaberwoke
11/30/2021 7:46 pm
Pillar of the Community
517 Posts
 Posted 11/30/2021  9:19 pm  Show Profile   Bookmark this reply Add Numister to your friends list Get a Link to this Reply

Quote:
I found a B-day gift for my daughter who's "nom de plume"/pseudonym for her email has always been "phoenixdraco". It's the 2017 Australian Phoenix Dragon 1 oz from the Perth Mint. What a find for my purpose as a gift, don't you think?!



Quote:
What am I missing?


Girls like coins for their birthday present?
Pillar of the Community
United States
3606 Posts
 Posted 11/30/2021  10:24 pm  Show Profile   Bookmark this reply Add Zurie to your friends list Get a Link to this Reply
I guess the only explanation would be if the Perth coin were hollow...

What a great idea for a gift, and it would make a super pendant! Perhaps the spec for the thickness is inaccurate, did that number come directly from the Perth Mint? I would suggest getting the Dragon/Phoenix coin first, then see if it's the same thickness as the ASE. It should be easy to find a bezel if it turns out to be the same size.
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Australia
14026 Posts
 Posted 11/30/2021  11:30 pm  Show Profile   Bookmark this reply Add Sap to your friends list Get a Link to this Reply
These particular Perth Mint coins are made in what they call "high relief". The rim is extra thick, and the design is sunk down into the coin. In effect, the coin is shaped like a biconcave lens. And biconcave lenses have very thick rims.

So Zurie is partly right: the coin is "hollow". Except the hollowness is all on the outside of the coin, rather than the inside.

Or look at it this way. A piece of pure silver weighing 1 troy ounce and with a diameter of 40.6mm must, by the laws of physics, have a volume of 2.965 cubic centimetres. The laws of mathematics then tell us that a perfectly flat, uniform blank disk with a diameter of 40.6mm and a volume of 2.965 cm3 must have a height, or thickness, of 2.29 mm. Therefore a 1 ounce pure silver coin that is 40.6 mm diameter cannot be thinner than 2.29mm, without breaking the laws of physics - but it can be thicker, if the shape deviates from a perfectly flat, featureless cylinder. A silver eagle deviates just a little - it does have a rim, and some relief in the design. Your Phoenix coin deviates a lot more.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
Pillar of the Community
United States
1277 Posts
 Posted 12/01/2021  12:06 am  Show Profile   Bookmark this reply Add Albert to your friends list Get a Link to this Reply
"Thickness" of a coin can be tricky.
Measured at the rim is one thing (maybe the thickest measure in many cases), or measured on the devices (high portions) is another thing, and measured on the field (low flat portion) is yet another (maybe the most thin). Check out a simulated but crude drawing side view and imagine this profile to be a coin. How exactly would one measure "thickness"?
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United States
3606 Posts
 Posted 12/01/2021  12:12 am  Show Profile   Bookmark this reply Add Zurie to your friends list Get a Link to this Reply
@Sap, that explanation makes perfect sense, especially now that I've seen a picture of one. It's a very cool coin!


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Australia
14026 Posts
 Posted 12/01/2021  06:00 am  Show Profile   Bookmark this reply Add Sap to your friends list Get a Link to this Reply
It should perhaps be pointed out that (again, laws of physics) the average thickness of the coin must still be 2.29 mm. So if the edges are 4mm thick, then the centre of the coin must be considerably thinner than 2.29 mm.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis
Valued Member
United States
74 Posts
 Posted 12/01/2021  11:13 am  Show Profile   Bookmark this reply Add jaberwoke to your friends list Get a Link to this Reply
Thank you all for the help. I see now that it's a high relief which would push the metal towards the rim and make it higher/thicker
Pillar of the Community
United States
3606 Posts
 Posted 12/01/2021  11:40 am  Show Profile   Bookmark this reply Add Zurie to your friends list Get a Link to this Reply
If you can't find a bezel for it, you could always get a custom-made one:

https://www.etsy.com/listing/573307...phoenix-1-oz
Pillar of the Community
Australia
1026 Posts
 Posted 12/01/2021  4:21 pm  Show Profile   Bookmark this reply Add David Graham to your friends list Get a Link to this Reply
Given she seems to be a Harry Potter fan, maybe this one:
https://collectcoins.com/2020-fiji-...draco-malfoy
Can't find any coins featuring Fawkes though.
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