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 Replies: 9 / Views: 1,163 |
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Valued Member
United States
75 Posts |
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
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Pillar of the Community
Singapore
631 Posts |
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?  |
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Pillar of the Community
 United States
5663 Posts |
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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Moderator
 Australia
16810 Posts |
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
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Pillar of the Community
United States
1912 Posts |
"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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Pillar of the Community
United States
5663 Posts |
@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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Moderator
Australia
16810 Posts |
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
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Valued Member
 United States
75 Posts |
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
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Pillar of the Community
United States
5663 Posts |
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Pillar of the Community
Australia
1610 Posts |
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Replies: 9 / Views: 1,163 |
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Posted 11/30/2021 10:24 pm
